diff --git a/app/[locale]/calendar/page.tsx b/app/[locale]/calendar/page.tsx
index ac8c2e61..0679488a 100644
--- a/app/[locale]/calendar/page.tsx
+++ b/app/[locale]/calendar/page.tsx
@@ -30,6 +30,9 @@ import { ICalImportModal } from "@/components/calendar/ical-import-modal";
 import { ICalSubscriptionModal } from "@/components/calendar/ical-subscription-modal";
 import { RecurrenceScopeDialog, type RecurrenceEditScope } from "@/components/calendar/recurrence-scope-dialog";
 import { NavigationRail } from "@/components/layout/navigation-rail";
+import { SidebarAppsModal } from "@/components/layout/sidebar-apps-modal";
+import { InlineAppView } from "@/components/layout/inline-app-view";
+import { useSidebarApps } from "@/hooks/use-sidebar-apps";
 import { ResizeHandle } from "@/components/layout/resize-handle";
 import { cn } from "@/lib/utils";
 import type { CalendarEvent, CalendarParticipant } from "@/lib/jmap/types";
@@ -48,6 +51,7 @@ export default function CalendarPage() {
   const router = useRouter();
   const t = useTranslations("calendar");
   const isMobile = useIsMobile();
+  const { showAppsModal, inlineApp, loadedApps, handleManageApps, handleInlineApp, closeInlineApp, closeAppsModal } = useSidebarApps();
   const { client, isAuthenticated, logout, checkAuth, isLoading: authLoading } = useAuthStore();
   const [initialCheckDone, setInitialCheckDone] = useState(() => useAuthStore.getState().isAuthenticated && !!useAuthStore.getState().client);
   const { quota, isPushConnected } = useEmailStore();
@@ -703,12 +707,20 @@ export default function CalendarPage() {
             quota={quota}
             isPushConnected={isPushConnected}
             onLogout={() => { logout(); router.push('/login'); }}
+            onManageApps={handleManageApps}
+            onInlineApp={handleInlineApp}
+            onCloseInlineApp={closeInlineApp}
+            activeAppId={inlineApp?.id ?? null}
           />
         </div>
       )}
 
+      {inlineApp && (
+        <InlineAppView apps={loadedApps} activeAppId={inlineApp!.id} onClose={closeInlineApp} className="flex-1" />
+      )}
+
       {/* Sidebar - full height */}
-      {!isMobile && (
+      {!isMobile && !inlineApp && (
         <>
           <div
             className={cn(
@@ -748,6 +760,7 @@ export default function CalendarPage() {
         </>
       )}
 
+      {!inlineApp && (
       <div className="flex flex-col flex-1 min-w-0">
         <CalendarToolbar
           selectedDate={selectedDate}
@@ -802,12 +815,19 @@ export default function CalendarPage() {
             </Button>
           )}
         </div>
-
-        {/* Mobile Bottom Navigation */}
-        {isMobile && (
-          <NavigationRail orientation="horizontal" />
-        )}
       </div>
+      )}
+
+      {/* Mobile Bottom Navigation */}
+      {isMobile && (
+        <NavigationRail
+          orientation="horizontal"
+          onManageApps={handleManageApps}
+          onInlineApp={handleInlineApp}
+          onCloseInlineApp={closeInlineApp}
+          activeAppId={inlineApp?.id ?? null}
+        />
+      )}
 
       {detailEvent && detailAnchorRect && (
         <EventDetailPopover
@@ -859,6 +879,7 @@ export default function CalendarPage() {
         />
       )}
 
+      <SidebarAppsModal isOpen={showAppsModal} onClose={closeAppsModal} />
       <RecurrenceScopeDialog
         isOpen={!!pendingScopeAction}
         actionType={pendingScopeAction?.type || "edit"}
diff --git a/app/[locale]/contacts/page.tsx b/app/[locale]/contacts/page.tsx
index be13da5e..695b7b56 100644
--- a/app/[locale]/contacts/page.tsx
+++ b/app/[locale]/contacts/page.tsx
@@ -20,6 +20,9 @@ import { useEmailStore } from "@/stores/email-store";
 import { toast } from "@/stores/toast-store";
 import { cn } from "@/lib/utils";
 import { NavigationRail } from "@/components/layout/navigation-rail";
+import { SidebarAppsModal } from "@/components/layout/sidebar-apps-modal";
+import { InlineAppView } from "@/components/layout/inline-app-view";
+import { useSidebarApps } from "@/hooks/use-sidebar-apps";
 import { ResizeHandle } from "@/components/layout/resize-handle";
 import { useIsMobile } from "@/hooks/use-media-query";
 import type { ContactCard } from "@/lib/jmap/types";
@@ -38,6 +41,7 @@ export default function ContactsPage() {
   const router = useRouter();
   const t = useTranslations("contacts");
   const { client, isAuthenticated, logout, checkAuth, isLoading: authLoading } = useAuthStore();
+  const { showAppsModal, inlineApp, loadedApps, handleManageApps, handleInlineApp, closeInlineApp, closeAppsModal } = useSidebarApps();
   const [initialCheckDone, setInitialCheckDone] = useState(() => useAuthStore.getState().isAuthenticated && !!useAuthStore.getState().client);
   const { quota, isPushConnected } = useEmailStore();
   const {
@@ -476,12 +480,19 @@ export default function ContactsPage() {
             quota={quota}
             isPushConnected={isPushConnected}
             onLogout={() => { logout(); router.push('/login'); }}
+            onManageApps={handleManageApps}
+            onInlineApp={handleInlineApp}
+            onCloseInlineApp={closeInlineApp}
+            activeAppId={inlineApp?.id ?? null}
           />
         </div>
       )}
 
       <div className="flex flex-col flex-1 min-w-0">
-        <div className="flex flex-1 min-h-0">
+        {inlineApp && (
+          <InlineAppView apps={loadedApps} activeAppId={inlineApp!.id} onClose={closeInlineApp} />
+        )}
+        <div className={cn("flex flex-1 min-h-0", inlineApp && "hidden")}>
           {showListPanel && (
             <>
               {/* Panel 1: Categories sidebar */}
@@ -582,10 +593,17 @@ export default function ContactsPage() {
         </div>
 
         {isMobile && (
-          <NavigationRail orientation="horizontal" />
+          <NavigationRail
+            orientation="horizontal"
+            onManageApps={handleManageApps}
+            onInlineApp={handleInlineApp}
+            onCloseInlineApp={closeInlineApp}
+            activeAppId={inlineApp?.id ?? null}
+          />
         )}
       </div>
 
+      <SidebarAppsModal isOpen={showAppsModal} onClose={closeAppsModal} />
       <ConfirmDialog {...confirmDialogProps} />
     </div>
   );
diff --git a/app/[locale]/files/page.tsx b/app/[locale]/files/page.tsx
index e660838d..c35cb02d 100644
--- a/app/[locale]/files/page.tsx
+++ b/app/[locale]/files/page.tsx
@@ -13,6 +13,9 @@ import { useFileStore } from "@/stores/file-store";
 import { toast } from "@/stores/toast-store";
 import { cn } from "@/lib/utils";
 import { NavigationRail } from "@/components/layout/navigation-rail";
+import { SidebarAppsModal } from "@/components/layout/sidebar-apps-modal";
+import { InlineAppView } from "@/components/layout/inline-app-view";
+import { useSidebarApps } from "@/hooks/use-sidebar-apps";
 import { useIsMobile } from "@/hooks/use-media-query";
 import { FileBrowser } from "@/components/files/file-browser";
 import { ImagePreviewModal } from "@/components/files/image-preview-modal";
@@ -24,6 +27,7 @@ export default function FilesPage() {
   const router = useRouter();
   const t = useTranslations("files");
   const { isAuthenticated, logout, checkAuth, isLoading: authLoading, client } = useAuthStore();
+  const { showAppsModal, inlineApp, loadedApps, handleManageApps, handleInlineApp, closeInlineApp, closeAppsModal } = useSidebarApps();
   const [initialCheckDone, setInitialCheckDone] = useState(() => useAuthStore.getState().isAuthenticated && !!useAuthStore.getState().client);
   const { quota, isPushConnected } = useEmailStore();
   const {
@@ -354,12 +358,19 @@ export default function FilesPage() {
             quota={quota}
             isPushConnected={isPushConnected}
             onLogout={() => { logout(); router.push('/login'); }}
+            onManageApps={handleManageApps}
+            onInlineApp={handleInlineApp}
+            onCloseInlineApp={closeInlineApp}
+            activeAppId={inlineApp?.id ?? null}
           />
         </div>
       )}
 
       <div className="flex flex-col flex-1 min-w-0">
-        <div className="flex flex-1 min-h-0">
+        {inlineApp && (
+          <InlineAppView apps={loadedApps} activeAppId={inlineApp!.id} onClose={closeInlineApp} />
+        )}
+        <div className={cn("flex flex-1 min-h-0", inlineApp && "hidden")}>
           <div className="flex-1 min-w-0 flex flex-col">
             {folderLayout !== "sidebar" && (
               <div className={cn("p-4 border-b border-border", isMobile && "px-3 py-3")}>
@@ -433,7 +444,13 @@ export default function FilesPage() {
         </div>
 
         {isMobile && (
-          <NavigationRail orientation="horizontal" />
+          <NavigationRail
+            orientation="horizontal"
+            onManageApps={handleManageApps}
+            onInlineApp={handleInlineApp}
+            onCloseInlineApp={closeInlineApp}
+            activeAppId={inlineApp?.id ?? null}
+          />
         )}
       </div>
 
@@ -457,6 +474,7 @@ export default function FilesPage() {
         />
       )}
 
+      <SidebarAppsModal isOpen={showAppsModal} onClose={closeAppsModal} />
       <ConfirmDialog {...confirmDialogProps} />
     </div>
   );
diff --git a/app/[locale]/page.tsx b/app/[locale]/page.tsx
index 11e14c39..4d76c768 100644
--- a/app/[locale]/page.tsx
+++ b/app/[locale]/page.tsx
@@ -35,6 +35,9 @@ import { DragDropProvider } from "@/contexts/drag-drop-context";
 import { isFilterEmpty, activeFilterCount } from "@/lib/jmap/search-utils";
 import { WelcomeBanner } from "@/components/ui/welcome-banner";
 import { NavigationRail } from "@/components/layout/navigation-rail";
+import { SidebarAppsModal } from "@/components/layout/sidebar-apps-modal";
+import { InlineAppView } from "@/components/layout/inline-app-view";
+import { useSidebarApps } from "@/hooks/use-sidebar-apps";
 import { Input } from "@/components/ui/input";
 import { FilePreviewModal } from "@/components/files/file-preview-modal";
 import { isFilePreviewable } from "@/lib/file-preview";
@@ -53,6 +56,7 @@ export default function Home() {
   const [composerDraftText, setComposerDraftText] = useState("");
   const [pendingDraft, setPendingDraft] = useState<ComposerDraftData | null>(null);
   const { dialogProps: confirmDialogProps, confirm: confirmDialog } = useConfirmDialog();
+  const { showAppsModal, inlineApp, loadedApps, handleManageApps, handleInlineApp, closeInlineApp, closeAppsModal } = useSidebarApps();
   const [initialCheckDone, setInitialCheckDone] = useState(() => useAuthStore.getState().isAuthenticated && !!useAuthStore.getState().client);
   const [showShortcutsModal, setShowShortcutsModal] = useState(false);
   const [showAdvancedFields, setShowAdvancedFields] = useState(false);
@@ -1007,12 +1011,20 @@ export default function Home() {
               isPushConnected={isPushConnected}
               onLogout={handleLogout}
               onShowShortcuts={() => setShowShortcutsModal(true)}
+              onManageApps={handleManageApps}
+              onInlineApp={handleInlineApp}
+              onCloseInlineApp={closeInlineApp}
+              activeAppId={inlineApp?.id ?? null}
             />
           </div>
         )}
 
+        {inlineApp && (
+          <InlineAppView apps={loadedApps} activeAppId={inlineApp!.id} onClose={closeInlineApp} className="flex-1" />
+        )}
+
         {/* Mobile/Tablet Sidebar Overlay Backdrop */}
-        {(isMobile || isTablet) && sidebarOpen && (
+        {(isMobile || isTablet) && sidebarOpen && !inlineApp && (
           <div
             className="fixed inset-0 bg-black/50 z-40 lg:hidden"
             onClick={() => setSidebarOpen(false)}
@@ -1029,7 +1041,8 @@ export default function Home() {
             "max-lg:transform max-lg:transition-transform max-lg:duration-300 max-lg:ease-in-out",
             !sidebarOpen && "max-lg:-translate-x-full",
             // Desktop: normal flow
-            "lg:relative lg:translate-x-0"
+            "lg:relative lg:translate-x-0",
+            inlineApp && "hidden"
           )}
           style={!isMobile && !isTablet ? { width: sidebarCollapsed ? 64 : sidebarWidth } : undefined}
         >
@@ -1055,7 +1068,7 @@ export default function Home() {
         </div>
 
         {/* Sidebar resize handle (desktop only, hidden when collapsed) */}
-        {!isMobile && !isTablet && !sidebarCollapsed && (
+        {!isMobile && !isTablet && !sidebarCollapsed && !inlineApp && (
           <ResizeHandle
             onResizeStart={() => { dragStartWidth.current = sidebarWidth; setIsResizing(true); }}
             onResize={(delta) => setSidebarWidth(dragStartWidth.current + delta)}
@@ -1065,7 +1078,7 @@ export default function Home() {
         )}
 
         {/* Main Content Area */}
-        <div className="flex flex-col flex-1 min-w-0 h-full">
+        <div className={cn("flex flex-col flex-1 min-w-0 h-full", inlineApp && "hidden")}>
           <div className="flex flex-1 min-h-0">
           {/* Email List - full width on mobile, fixed width on tablet/desktop */}
           <div
@@ -1552,7 +1565,13 @@ export default function Home() {
 
           {/* Bottom Navigation - mobile and tablet */}
           {(isMobile || isTablet) && activeView !== "viewer" && (
-            <NavigationRail orientation="horizontal" />
+            <NavigationRail
+              orientation="horizontal"
+              onManageApps={handleManageApps}
+              onInlineApp={handleInlineApp}
+              onCloseInlineApp={closeInlineApp}
+              activeAppId={inlineApp?.id ?? null}
+            />
           )}
         </div>
         </div>
@@ -1575,6 +1594,7 @@ export default function Home() {
         {/* Screen reader live region for dynamic status announcements */}
         <div className="sr-only" aria-live="polite" aria-atomic="true" id="sr-status" />
 
+        <SidebarAppsModal isOpen={showAppsModal} onClose={closeAppsModal} />
         <ConfirmDialog {...confirmDialogProps} />
       </div>
     </DragDropProvider>
diff --git a/app/[locale]/settings/page.tsx b/app/[locale]/settings/page.tsx
index 4a682019..66a3e9a0 100644
--- a/app/[locale]/settings/page.tsx
+++ b/app/[locale]/settings/page.tsx
@@ -23,6 +23,7 @@ import {
   Wrench,
   BookUser,
   KeyRound,
+  PanelLeftClose,
   type LucideIcon,
 } from 'lucide-react';
 import { Button } from '@/components/ui/button';
@@ -42,15 +43,19 @@ import { AccountSecuritySettings } from '@/components/settings/account-security-
 import { FilesSettingsComponent } from '@/components/settings/files-settings';
 import { ContactsSettings } from '@/components/settings/contacts-settings';
 import { SmimeSettings } from '@/components/settings/smime-settings';
+import { SidebarAppsSettings } from '@/components/settings/sidebar-apps-settings';
 import { useAuthStore } from '@/stores/auth-store';
 import { useEmailStore } from '@/stores/email-store';
 import { useIsDesktop } from '@/hooks/use-media-query';
 import { NavigationRail } from '@/components/layout/navigation-rail';
+import { SidebarAppsModal } from '@/components/layout/sidebar-apps-modal';
+import { InlineAppView } from '@/components/layout/inline-app-view';
+import { useSidebarApps } from '@/hooks/use-sidebar-apps';
 import { ResizeHandle } from '@/components/layout/resize-handle';
 import { useConfig } from '@/hooks/use-config';
 import { cn } from '@/lib/utils';
 
-type Tab = 'appearance' | 'email' | 'account' | 'security' | 'identities' | 'encryption' | 'vacation' | 'calendar' | 'contacts' | 'filters' | 'templates' | 'folders' | 'keywords' | 'files' | 'advanced';
+type Tab = 'appearance' | 'email' | 'account' | 'security' | 'identities' | 'encryption' | 'vacation' | 'calendar' | 'contacts' | 'filters' | 'templates' | 'folders' | 'keywords' | 'files' | 'sidebar_apps' | 'advanced';
 type TabGroup = 'general' | 'account' | 'organization' | 'apps' | 'system';
 
 interface TabDef {
@@ -75,6 +80,7 @@ const tabIcons: Record<Tab, LucideIcon> = {
   folders: FolderOpen,
   keywords: Tags,
   files: HardDrive,
+  sidebar_apps: PanelLeftClose,
   advanced: Wrench,
 };
 
@@ -85,6 +91,7 @@ export default function SettingsPage() {
   const t = useTranslations('settings');
   const tSidebar = useTranslations('sidebar');
   const { client, isAuthenticated, logout, checkAuth, isLoading: authLoading } = useAuthStore();
+  const { showAppsModal, inlineApp, loadedApps, handleManageApps, handleInlineApp, closeInlineApp, closeAppsModal } = useSidebarApps();
   const [initialCheckDone, setInitialCheckDone] = useState(() => useAuthStore.getState().isAuthenticated && !!useAuthStore.getState().client);
   const { quota, isPushConnected } = useEmailStore();
   const { stalwartFeaturesEnabled } = useConfig();
@@ -143,6 +150,7 @@ export default function SettingsPage() {
     ...(supportsCalendar ? [{ id: 'calendar' as Tab, label: t('tabs.calendar'), icon: tabIcons.calendar, group: 'apps' as TabGroup }] : []),
     { id: 'contacts', label: t('tabs.contacts'), icon: tabIcons.contacts, group: 'apps' },
     ...(supportsFiles ? [{ id: 'files' as Tab, label: t('tabs.files'), icon: tabIcons.files, group: 'apps' as TabGroup }] : []),
+    { id: 'sidebar_apps', label: t('tabs.sidebar_apps'), icon: tabIcons.sidebar_apps, group: 'apps' },
     { id: 'advanced', label: t('tabs.advanced'), icon: tabIcons.advanced, group: 'system' },
   ];
 
@@ -181,6 +189,7 @@ export default function SettingsPage() {
       {activeTab === 'folders' && <FolderSettings />}
       {activeTab === 'keywords' && <KeywordSettings />}
       {activeTab === 'files' && <FilesSettingsComponent />}
+      {activeTab === 'sidebar_apps' && <SidebarAppsSettings />}
       {activeTab === 'advanced' && <AdvancedSettings />}
     </>
   );
@@ -212,7 +221,14 @@ export default function SettingsPage() {
           </div>
 
           {/* Bottom Navigation */}
-          <NavigationRail orientation="horizontal" />
+          <NavigationRail
+            orientation="horizontal"
+            onManageApps={handleManageApps}
+            onInlineApp={handleInlineApp}
+            onCloseInlineApp={closeInlineApp}
+            activeAppId={inlineApp?.id ?? null}
+          />
+          <SidebarAppsModal isOpen={showAppsModal} onClose={closeAppsModal} />
         </div>
       );
     }
@@ -280,7 +296,14 @@ export default function SettingsPage() {
         </div>
 
         {/* Bottom Navigation */}
-        <NavigationRail orientation="horizontal" />
+        <NavigationRail
+          orientation="horizontal"
+          onManageApps={handleManageApps}
+          onInlineApp={handleInlineApp}
+          onCloseInlineApp={closeInlineApp}
+          activeAppId={inlineApp?.id ?? null}
+        />
+        <SidebarAppsModal isOpen={showAppsModal} onClose={closeAppsModal} />
       </div>
     );
   }
@@ -295,9 +318,18 @@ export default function SettingsPage() {
           quota={quota}
           isPushConnected={isPushConnected}
           onLogout={() => { logout(); router.push('/login'); }}
+          onManageApps={handleManageApps}
+          onInlineApp={handleInlineApp}
+          onCloseInlineApp={closeInlineApp}
+          activeAppId={inlineApp?.id ?? null}
         />
       </div>
 
+      {inlineApp && (
+        <InlineAppView apps={loadedApps} activeAppId={inlineApp!.id} onClose={closeInlineApp} className="flex-1" />
+      )}
+      {!inlineApp && (
+      <>
       {/* Settings Sidebar */}
       <div
         className={cn(
@@ -385,6 +417,9 @@ export default function SettingsPage() {
           </div>
         </div>
       </div>
+      </>
+      )}
+      <SidebarAppsModal isOpen={showAppsModal} onClose={closeAppsModal} />
     </div>
   );
 }
diff --git a/components/layout/icon-picker.tsx b/components/layout/icon-picker.tsx
new file mode 100644
index 00000000..80fc1945
--- /dev/null
+++ b/components/layout/icon-picker.tsx
@@ -0,0 +1,149 @@
+'use client';
+
+import { useState, useMemo, useRef, useEffect, useCallback } from 'react';
+import { useTranslations } from 'next-intl';
+import { icons as lucideIcons, type LucideIcon } from 'lucide-react';
+import { Search, X } from 'lucide-react';
+import { cn } from '@/lib/utils';
+import { Input } from '@/components/ui/input';
+
+// Curated list of commonly useful icons, organized by category
+const POPULAR_ICONS = [
+  // Communication
+  'Globe', 'Rss', 'Radio', 'Podcast', 'MessageCircle', 'MessageSquare', 'MessagesSquare',
+  'Phone', 'Video', 'Webcam', 'Headphones', 'Mic',
+  // Productivity
+  'FileText', 'FileSpreadsheet', 'Notebook', 'BookOpen', 'ClipboardList',
+  'ListTodo', 'CheckSquare', 'SquareKanban', 'Kanban', 'Trello',
+  'PenLine', 'Pencil', 'Edit', 'NotebookPen',
+  // Dev / Tech
+  'Code', 'Terminal', 'Braces', 'Bug', 'Database', 'Server', 'Cpu',
+  'HardDrive', 'Monitor', 'Laptop', 'Smartphone', 'Tablet',
+  'Wifi', 'Cloud', 'CloudDownload', 'CloudUpload',
+  // Social / People
+  'Users', 'UserPlus', 'UserCircle', 'Contact', 'PersonStanding',
+  'Heart', 'ThumbsUp', 'Star', 'Award', 'Trophy', 'Crown',
+  // Media
+  'Image', 'Camera', 'Film', 'Music', 'Play', 'Tv', 'Youtube', 'Clapperboard',
+  'Palette', 'Paintbrush', 'Brush',
+  // Navigation / Location
+  'Map', 'MapPin', 'Navigation', 'Compass', 'Home', 'Building', 'Building2',
+  'Landmark', 'Store', 'Warehouse',
+  // Finance
+  'DollarSign', 'Euro', 'CreditCard', 'Wallet', 'Receipt', 'PiggyBank',
+  'TrendingUp', 'BarChart', 'BarChart3', 'LineChart', 'PieChart',
+  // Security
+  'Shield', 'ShieldCheck', 'Lock', 'Unlock', 'Key', 'Fingerprint', 'Eye',
+  // Science / Health
+  'Beaker', 'Atom', 'Dna', 'Microscope', 'Stethoscope', 'HeartPulse', 'Pill',
+  'Syringe', 'Thermometer',
+  // Nature
+  'Sun', 'Moon', 'CloudSun', 'Snowflake', 'Zap', 'Flame',
+  'TreePine', 'Flower', 'Leaf', 'Mountain', 'Waves',
+  // Tools
+  'Wrench', 'Hammer', 'Scissors', 'Ruler', 'Magnet',
+  'Package', 'Gift', 'Box', 'Archive',
+  // Transport
+  'Car', 'Bike', 'Bus', 'Train', 'Plane', 'Ship', 'Rocket',
+  // Food
+  'Coffee', 'Wine', 'Beer', 'Pizza', 'Apple', 'Cake', 'CookingPot',
+  // Misc
+  'Gamepad2', 'Dice5', 'Puzzle', 'Sparkles', 'Wand2', 'Bot', 'BrainCircuit',
+  'Lightbulb', 'Bookmark', 'Flag', 'Bell', 'Clock', 'Timer',
+  'Link', 'ExternalLink', 'QrCode', 'Scan', 'LayoutGrid', 'Layers',
+  'Aperture', 'CircleDot', 'Target', 'Crosshair',
+];
+
+interface IconPickerProps {
+  value: string;
+  onChange: (iconName: string) => void;
+  className?: string;
+}
+
+export function IconPicker({ value, onChange, className }: IconPickerProps) {
+  const t = useTranslations('sidebar_apps');
+  const [search, setSearch] = useState('');
+  const [showAll, setShowAll] = useState(false);
+  const gridRef = useRef<HTMLDivElement>(null);
+
+  // Get all available icon names
+  const allIconNames = useMemo(() => {
+    return Object.keys(lucideIcons).filter(
+      k => /^[A-Z]/.test(k) && k !== 'createLucideIcon' && k !== 'Icon'
+    ).sort();
+  }, []);
+
+  const filteredIcons = useMemo(() => {
+    const source = showAll ? allIconNames : POPULAR_ICONS.filter(name => name in lucideIcons);
+    if (!search.trim()) return source;
+    const q = search.toLowerCase();
+    return source.filter(name => name.toLowerCase().includes(q));
+  }, [search, showAll, allIconNames]);
+
+  const renderIcon = useCallback((name: string) => {
+    const IconComponent = lucideIcons[name as keyof typeof lucideIcons] as LucideIcon | undefined;
+    if (!IconComponent) return null;
+    return <IconComponent className="w-5 h-5" />;
+  }, []);
+
+  return (
+    <div className={cn('space-y-2', className)}>
+      <div className="flex items-center gap-2">
+        <div className="relative flex-1">
+          <Search className="absolute left-2.5 top-1/2 -translate-y-1/2 w-3.5 h-3.5 text-muted-foreground" />
+          <Input
+            value={search}
+            onChange={(e) => setSearch(e.target.value)}
+            placeholder={t('search_icons')}
+            className="pl-8 h-8 text-xs"
+          />
+          {search && (
+            <button
+              onClick={() => setSearch('')}
+              className="absolute right-2 top-1/2 -translate-y-1/2 text-muted-foreground hover:text-foreground"
+            >
+              <X className="w-3 h-3" />
+            </button>
+          )}
+        </div>
+        <button
+          onClick={() => setShowAll(!showAll)}
+          className={cn(
+            'text-xs px-2 py-1 rounded-md border transition-colors whitespace-nowrap',
+            showAll
+              ? 'bg-primary/10 text-primary border-primary/30'
+              : 'bg-muted text-muted-foreground border-border hover:text-foreground'
+          )}
+        >
+          {showAll ? t('show_popular') : t('show_all')}
+        </button>
+      </div>
+      <div
+        ref={gridRef}
+        className="grid grid-cols-8 gap-1 max-h-[200px] overflow-y-auto p-1 border rounded-md bg-muted/30"
+      >
+        {filteredIcons.map(name => (
+          <button
+            key={name}
+            type="button"
+            onClick={() => onChange(name)}
+            title={name}
+            className={cn(
+              'flex items-center justify-center w-8 h-8 rounded-md transition-colors',
+              value === name
+                ? 'bg-primary text-primary-foreground'
+                : 'hover:bg-muted text-muted-foreground hover:text-foreground'
+            )}
+          >
+            {renderIcon(name)}
+          </button>
+        ))}
+        {filteredIcons.length === 0 && (
+          <p className="col-span-8 py-4 text-center text-xs text-muted-foreground">
+            {t('no_icons_found')}
+          </p>
+        )}
+      </div>
+    </div>
+  );
+}
diff --git a/components/layout/inline-app-view.tsx b/components/layout/inline-app-view.tsx
new file mode 100644
index 00000000..af7dc32d
--- /dev/null
+++ b/components/layout/inline-app-view.tsx
@@ -0,0 +1,49 @@
+'use client';
+
+import { X } from 'lucide-react';
+import { cn } from '@/lib/utils';
+import type { InlineAppState } from '@/hooks/use-sidebar-apps';
+
+interface InlineAppViewProps {
+  apps: InlineAppState[];
+  activeAppId: string;
+  onClose: () => void;
+  className?: string;
+}
+
+export function InlineAppView({ apps, activeAppId, onClose, className }: InlineAppViewProps) {
+  const activeApp = apps.find((a) => a.id === activeAppId);
+
+  return (
+    <div className={cn('flex flex-col h-full bg-background', className)}>
+      {/* Header bar */}
+      <div className="flex items-center justify-between px-4 py-2 border-b border-border bg-secondary/50 flex-shrink-0">
+        <h3 className="text-sm font-medium truncate">{activeApp?.name}</h3>
+        <button
+          onClick={onClose}
+          className="p-1 rounded-md hover:bg-muted transition-colors text-muted-foreground hover:text-foreground"
+          aria-label="Close"
+        >
+          <X className="w-4 h-4" />
+        </button>
+      </div>
+      {/* Iframes - active one visible, rest hidden but alive */}
+      <div className="flex-1 relative">
+        {apps.map((app) => (
+          <iframe
+            key={app.id}
+            src={app.url}
+            title={app.name}
+            className={cn(
+              'absolute inset-0 w-full h-full border-0',
+              app.id !== activeAppId && 'hidden'
+            )}
+            sandbox="allow-scripts allow-same-origin allow-forms allow-popups allow-popups-to-escape-sandbox"
+            referrerPolicy="no-referrer"
+            loading="lazy"
+          />
+        ))}
+      </div>
+    </div>
+  );
+}
diff --git a/components/layout/navigation-rail.tsx b/components/layout/navigation-rail.tsx
index a8ba1ecb..13f7b933 100644
--- a/components/layout/navigation-rail.tsx
+++ b/components/layout/navigation-rail.tsx
@@ -2,12 +2,14 @@
 
 import { useState, useRef, useEffect, useCallback } from "react";
 import { createPortal } from "react-dom";
-import { Mail, Calendar, BookUser, HardDrive, Settings, LogOut, Keyboard } from "lucide-react";
+import { Mail, Calendar, BookUser, HardDrive, Settings, LogOut, Keyboard, Plus } from "lucide-react";
+import { icons as lucideIcons, type LucideIcon } from "lucide-react";
 import { usePathname, Link } from "@/i18n/navigation";
 import { useTranslations } from "next-intl";
 import { useCalendarStore } from "@/stores/calendar-store";
 import { useEmailStore } from "@/stores/email-store";
 import { useWebDAVStore } from "@/stores/webdav-store";
+import { useSettingsStore } from "@/stores/settings-store";
 import { cn, formatFileSize } from "@/lib/utils";
 
 interface NavItem {
@@ -27,6 +29,10 @@ interface NavigationRailProps {
   isPushConnected?: boolean;
   onLogout?: () => void;
   onShowShortcuts?: () => void;
+  onManageApps?: () => void;
+  onInlineApp?: (appId: string, url: string, name: string) => void;
+  onCloseInlineApp?: () => void;
+  activeAppId?: string | null;
 }
 
 function StorageQuotaCircle({ quota, usagePercent }: { quota: { used: number; total: number }; usagePercent: number }) {
@@ -138,12 +144,17 @@ export function NavigationRail({
   isPushConnected,
   onLogout,
   onShowShortcuts,
+  onManageApps,
+  onInlineApp,
+  onCloseInlineApp,
+  activeAppId,
 }: NavigationRailProps) {
   const t = useTranslations("sidebar");
   const pathname = usePathname();
   const { supportsCalendar } = useCalendarStore();
   const { mailboxes } = useEmailStore();
   const { supportsWebDAV } = useWebDAVStore();
+  const sidebarApps = useSettingsStore((s) => s.sidebarApps);
   const inboxUnread = mailboxes.find(m => m.role === "inbox")?.unreadEmails || 0;
 
   const navItems: NavItem[] = [
@@ -151,12 +162,14 @@ export function NavigationRail({
     { id: "calendar", icon: Calendar, labelKey: "calendar", href: "/calendar", hidden: !supportsCalendar },
     { id: "contacts", icon: BookUser, labelKey: "contacts", href: "/contacts" },
     { id: "files", icon: HardDrive, labelKey: "files", href: "/files", hidden: supportsWebDAV === false },
-    { id: "settings", icon: Settings, labelKey: "settings", href: "/settings" },
   ];
 
+  const isSettingsActive = !activeAppId && pathname.startsWith("/settings");
+
   const visibleItems = navItems.filter((item) => !item.hidden);
 
   const getIsActive = (href: string) => {
+    if (activeAppId) return false;
     if (href === "/") {
       return pathname === "/" || pathname === "";
     }
@@ -177,6 +190,7 @@ export function NavigationRail({
             <Link
               key={item.id}
               href={item.href}
+              onClick={activeAppId ? () => onCloseInlineApp?.() : undefined}
               className={cn(
                 "flex flex-col items-center justify-center gap-1 py-2 px-3 min-w-[64px] min-h-[44px]",
                 "transition-colors duration-150",
@@ -201,6 +215,52 @@ export function NavigationRail({
             </Link>
           );
         })}
+
+        {/* Custom sidebar apps */}
+        {sidebarApps.map((app) => {
+          const AppIcon = lucideIcons[app.icon as keyof typeof lucideIcons] as LucideIcon | undefined;
+          const isActive = activeAppId === app.id;
+          return (
+            <button
+              key={app.id}
+              onClick={() => {
+                if (isActive) {
+                  onCloseInlineApp?.();
+                } else if (app.openMode === 'tab') {
+                  window.open(app.url, '_blank', 'noopener,noreferrer');
+                } else {
+                  onInlineApp?.(app.id, app.url, app.name);
+                }
+              }}
+              className={cn(
+                "flex flex-col items-center justify-center gap-1 py-2 px-3 min-w-[64px] min-h-[44px]",
+                "transition-colors duration-150",
+                isActive
+                  ? "text-primary"
+                  : "text-muted-foreground hover:text-foreground"
+              )}
+            >
+              <div className="relative">
+                {AppIcon ? <AppIcon className="w-5 h-5" /> : null}
+                {isActive && (
+                  <span className="absolute -bottom-1 left-1/2 -translate-x-1/2 w-4 h-0.5 rounded-full bg-primary" />
+                )}
+              </div>
+              <span className="text-[10px] font-medium leading-tight truncate max-w-[64px]">{app.name}</span>
+            </button>
+          );
+        })}
+
+        {/* Manage apps button */}
+        {onManageApps && (
+          <button
+            onClick={onManageApps}
+            className="flex flex-col items-center justify-center gap-1 py-2 px-3 min-w-[64px] min-h-[44px] transition-colors duration-150 text-muted-foreground hover:text-foreground"
+          >
+            <Plus className="w-5 h-5" />
+            <span className="text-[10px] font-medium leading-tight">{t("add_app")}</span>
+          </button>
+        )}
       </nav>
     );
   }
@@ -230,6 +290,7 @@ export function NavigationRail({
             <Link
               key={item.id}
               href={item.href}
+              onClick={activeAppId ? () => onCloseInlineApp?.() : undefined}
               className={cn(
                 "relative flex items-center gap-2.5 rounded-md transition-colors duration-150",
                 collapsed
@@ -257,13 +318,90 @@ export function NavigationRail({
             </Link>
           );
         })}
+
+        {/* Custom sidebar apps */}
+        {sidebarApps.length > 0 && (
+          <div
+            className={cn(
+              "border-t",
+              collapsed ? "w-8 mx-auto my-1 pt-1" : "mx-2 my-0.5 pt-0.5"
+            )}
+            style={{ borderColor: 'rgba(128, 128, 128, 0.3)' }}
+          />
+        )}
+        {sidebarApps.map((app) => {
+          const AppIcon = lucideIcons[app.icon as keyof typeof lucideIcons] as LucideIcon | undefined;
+          const isActive = activeAppId === app.id;
+          return (
+            <button
+              key={app.id}
+              onClick={() => {
+                if (isActive) {
+                  onCloseInlineApp?.();
+                } else if (app.openMode === 'tab') {
+                  window.open(app.url, '_blank', 'noopener,noreferrer');
+                } else {
+                  onInlineApp?.(app.id, app.url, app.name);
+                }
+              }}
+              className={cn(
+                "relative flex items-center gap-2.5 rounded-md transition-colors duration-150",
+                collapsed
+                  ? "justify-center w-10 h-10"
+                  : "px-2.5 text-sm",
+                "max-lg:min-h-[44px]",
+                isActive
+                  ? "bg-primary/10 text-primary font-medium"
+                  : "text-muted-foreground hover:bg-muted hover:text-foreground"
+              )}
+              title={collapsed ? app.name : undefined}
+              style={collapsed ? undefined : { paddingBlock: 'var(--density-sidebar-py)' }}
+            >
+              {AppIcon ? <AppIcon className={cn("w-[18px] h-[18px] flex-shrink-0", isActive && "text-primary")} /> : null}
+              {!collapsed && <span className="truncate">{app.name}</span>}
+            </button>
+          );
+        })}
+
+        {/* Manage apps button */}
+        {onManageApps && (
+          <button
+            onClick={onManageApps}
+            className={cn(
+              "relative flex items-center gap-2.5 rounded-md transition-colors duration-150",
+              collapsed
+                ? "justify-center w-10 h-10"
+                : "px-2.5 text-sm",
+              "max-lg:min-h-[44px]",
+              "text-muted-foreground hover:bg-muted hover:text-foreground"
+            )}
+            title={collapsed ? t("add_app") : undefined}
+            style={collapsed ? undefined : { paddingBlock: 'var(--density-sidebar-py)' }}
+          >
+            <Plus className="w-[18px] h-[18px] flex-shrink-0" />
+            {!collapsed && <span className="truncate">{t("add_app")}</span>}
+          </button>
+        )}
       </nav>
 
-      {/* Footer: Storage Quota + Sign Out + Push Status */}
-      <div className="mt-auto flex flex-col items-center gap-2 pb-3 px-1 border-t border-border pt-2">
-        {quota && quota.total > 0 && (
-          <StorageQuotaCircle quota={quota} usagePercent={quotaUsagePercent} />
-        )}
+      {/* Footer: Settings + Help + Storage Quota + Sign Out + Push Status */}
+      <div className="mt-auto flex flex-col items-center gap-2 pb-3 px-1">
+        <Link
+          href="/settings"
+          onClick={activeAppId ? () => onCloseInlineApp?.() : undefined}
+          className={cn(
+            "flex items-center justify-center w-10 h-10 rounded-md transition-colors",
+            isSettingsActive
+              ? "bg-primary/10 text-primary"
+              : "text-muted-foreground hover:text-foreground hover:bg-muted"
+          )}
+          title={t("settings")}
+          aria-current={isSettingsActive ? "page" : undefined}
+        >
+          <Settings className="w-[18px] h-[18px]" />
+        </Link>
+
+        <div className="w-8 border-t" style={{ borderColor: 'rgba(128, 128, 128, 0.3)' }} />
 
         {onShowShortcuts && (
           <button
@@ -275,6 +413,10 @@ export function NavigationRail({
           </button>
         )}
 
+        {quota && quota.total > 0 && (
+          <StorageQuotaCircle quota={quota} usagePercent={quotaUsagePercent} />
+        )}
+
         {isPushConnected != null && (
           <span
             className="relative group"
diff --git a/components/layout/sidebar-apps-modal.tsx b/components/layout/sidebar-apps-modal.tsx
new file mode 100644
index 00000000..f451e4b6
--- /dev/null
+++ b/components/layout/sidebar-apps-modal.tsx
@@ -0,0 +1,355 @@
+'use client';
+
+import { useState, useCallback } from 'react';
+import { useTranslations } from 'next-intl';
+import { X, Plus, Pencil, Trash2, GripVertical, ExternalLink, PanelRight } from 'lucide-react';
+import { icons as lucideIcons, type LucideIcon } from 'lucide-react';
+import { cn } from '@/lib/utils';
+import { Button } from '@/components/ui/button';
+import { Input } from '@/components/ui/input';
+import { IconPicker } from './icon-picker';
+import { useSettingsStore, type SidebarApp } from '@/stores/settings-store';
+import { useFocusTrap } from '@/hooks/use-focus-trap';
+import { useConfirmDialog } from '@/hooks/use-confirm-dialog';
+import { ConfirmDialog } from '@/components/ui/confirm-dialog';
+
+interface SidebarAppFormData {
+  name: string;
+  url: string;
+  icon: string;
+  openMode: 'tab' | 'inline';
+}
+
+function SidebarAppForm({
+  app,
+  onSave,
+  onCancel,
+}: {
+  app?: SidebarApp;
+  onSave: (data: SidebarAppFormData) => void;
+  onCancel: () => void;
+}) {
+  const t = useTranslations('sidebar_apps');
+  const isEditing = !!app;
+
+  const [formData, setFormData] = useState<SidebarAppFormData>({
+    name: app?.name || '',
+    url: app?.url || '',
+    icon: app?.icon || 'Globe',
+    openMode: app?.openMode || 'tab',
+  });
+  const [errors, setErrors] = useState<Record<string, string>>({});
+
+  const validate = (): boolean => {
+    const newErrors: Record<string, string> = {};
+    if (!formData.name.trim()) {
+      newErrors.name = t('name_required');
+    }
+    if (!formData.url.trim()) {
+      newErrors.url = t('url_required');
+    } else {
+      try {
+        const parsed = new URL(formData.url);
+        if (!['http:', 'https:'].includes(parsed.protocol)) {
+          newErrors.url = t('url_invalid');
+        }
+      } catch {
+        newErrors.url = t('url_invalid');
+      }
+    }
+    if (!formData.icon) {
+      newErrors.icon = t('icon_required');
+    }
+    setErrors(newErrors);
+    return Object.keys(newErrors).length === 0;
+  };
+
+  const handleSubmit = (e: React.FormEvent) => {
+    e.preventDefault();
+    if (!validate()) return;
+    onSave(formData);
+  };
+
+  const SelectedIcon = formData.icon
+    ? (lucideIcons[formData.icon as keyof typeof lucideIcons] as LucideIcon | undefined)
+    : null;
+
+  return (
+    <form onSubmit={handleSubmit} className="space-y-4">
+      {/* Name */}
+      <div>
+        <label htmlFor="app-name" className="block text-sm font-medium mb-1">
+          {t('name_label')} <span className="text-destructive">*</span>
+        </label>
+        <Input
+          id="app-name"
+          type="text"
+          maxLength={50}
+          value={formData.name}
+          onChange={(e) => setFormData({ ...formData, name: e.target.value })}
+          placeholder={t('name_placeholder')}
+          className={errors.name ? 'border-destructive' : ''}
+        />
+        {errors.name && (
+          <p className="text-sm text-destructive mt-1">{errors.name}</p>
+        )}
+      </div>
+
+      {/* URL */}
+      <div>
+        <label htmlFor="app-url" className="block text-sm font-medium mb-1">
+          {t('url_label')} <span className="text-destructive">*</span>
+        </label>
+        <Input
+          id="app-url"
+          type="url"
+          maxLength={2048}
+          value={formData.url}
+          onChange={(e) => setFormData({ ...formData, url: e.target.value })}
+          placeholder="https://example.com"
+          className={errors.url ? 'border-destructive' : ''}
+        />
+        {errors.url && (
+          <p className="text-sm text-destructive mt-1">{errors.url}</p>
+        )}
+      </div>
+
+      {/* Open Mode */}
+      <div>
+        <label className="block text-sm font-medium mb-2">{t('open_mode_label')}</label>
+        <div className="flex gap-2">
+          <button
+            type="button"
+            onClick={() => setFormData({ ...formData, openMode: 'tab' })}
+            className={cn(
+              'flex items-center gap-2 px-3 py-2 rounded-md border text-sm transition-colors flex-1',
+              formData.openMode === 'tab'
+                ? 'bg-primary/10 border-primary/30 text-primary'
+                : 'border-border text-muted-foreground hover:text-foreground hover:border-muted-foreground'
+            )}
+          >
+            <ExternalLink className="w-4 h-4" />
+            {t('open_new_tab')}
+          </button>
+          <button
+            type="button"
+            onClick={() => setFormData({ ...formData, openMode: 'inline' })}
+            className={cn(
+              'flex items-center gap-2 px-3 py-2 rounded-md border text-sm transition-colors flex-1',
+              formData.openMode === 'inline'
+                ? 'bg-primary/10 border-primary/30 text-primary'
+                : 'border-border text-muted-foreground hover:text-foreground hover:border-muted-foreground'
+            )}
+          >
+            <PanelRight className="w-4 h-4" />
+            {t('open_inline')}
+          </button>
+        </div>
+      </div>
+
+      {/* Icon Picker */}
+      <div>
+        <label className="block text-sm font-medium mb-2">
+          {t('icon_label')} <span className="text-destructive">*</span>
+          {SelectedIcon && (
+            <span className="inline-flex items-center gap-1.5 ml-2 text-muted-foreground font-normal">
+              — <SelectedIcon className="w-4 h-4" /> {formData.icon}
+            </span>
+          )}
+        </label>
+        <IconPicker
+          value={formData.icon}
+          onChange={(icon) => setFormData({ ...formData, icon })}
+        />
+        {errors.icon && (
+          <p className="text-sm text-destructive mt-1">{errors.icon}</p>
+        )}
+      </div>
+
+      {/* Actions */}
+      <div className="flex justify-end gap-2 pt-2">
+        <Button type="button" variant="outline" onClick={onCancel}>
+          {t('cancel')}
+        </Button>
+        <Button type="submit">
+          {isEditing ? t('update') : t('add')}
+        </Button>
+      </div>
+    </form>
+  );
+}
+
+interface SidebarAppsModalProps {
+  isOpen: boolean;
+  onClose: () => void;
+}
+
+export function SidebarAppsModal({ isOpen, onClose }: SidebarAppsModalProps) {
+  const t = useTranslations('sidebar_apps');
+  const { sidebarApps, addSidebarApp, updateSidebarApp, removeSidebarApp } = useSettingsStore();
+  const [editingId, setEditingId] = useState<string | null>(null);
+  const [isCreating, setIsCreating] = useState(false);
+  const { dialogProps: confirmDialogProps, confirm: confirmDialog } = useConfirmDialog();
+
+  const modalRef = useFocusTrap({
+    isActive: isOpen,
+    onEscape: () => {
+      if (isCreating || editingId) {
+        setIsCreating(false);
+        setEditingId(null);
+      } else {
+        onClose();
+      }
+    },
+    restoreFocus: true,
+  });
+
+  const handleCreate = useCallback((data: SidebarAppFormData) => {
+    const id = `app-${Date.now()}-${Math.random().toString(36).slice(2, 7)}`;
+    addSidebarApp({ id, ...data });
+    setIsCreating(false);
+  }, [addSidebarApp]);
+
+  const handleUpdate = useCallback((id: string, data: SidebarAppFormData) => {
+    updateSidebarApp(id, data);
+    setEditingId(null);
+  }, [updateSidebarApp]);
+
+  const handleDelete = useCallback(async (app: SidebarApp) => {
+    const confirmed = await confirmDialog({
+      title: t('delete_confirm_title'),
+      message: t('delete_confirm', { name: app.name }),
+      confirmText: t('delete'),
+      variant: 'destructive',
+    });
+    if (!confirmed) return;
+    removeSidebarApp(app.id);
+  }, [removeSidebarApp, confirmDialog, t]);
+
+  if (!isOpen) return null;
+
+  return (
+    <div className="fixed inset-0 bg-black/50 backdrop-blur-[1px] flex items-center justify-center z-50 p-4 animate-in fade-in duration-150">
+      <div
+        ref={modalRef}
+        role="dialog"
+        aria-modal="true"
+        aria-labelledby="sidebar-apps-modal-title"
+        className={cn(
+          'bg-background border border-border rounded-lg shadow-xl',
+          'w-full max-w-2xl max-h-[90vh] overflow-hidden',
+          'animate-in zoom-in-95 duration-200'
+        )}
+      >
+        {/* Header */}
+        <div className="flex items-center justify-between px-6 py-4 border-b border-border">
+          <h2 id="sidebar-apps-modal-title" className="text-lg font-semibold text-foreground">
+            {t('modal_title')}
+          </h2>
+          <button
+            onClick={onClose}
+            className="p-1.5 rounded-md hover:bg-muted transition-colors text-muted-foreground hover:text-foreground"
+          >
+            <X className="w-5 h-5" />
+          </button>
+        </div>
+
+        {/* Content */}
+        <div className="p-6 overflow-y-auto max-h-[calc(90vh-80px)]">
+          {/* Create form */}
+          {isCreating && (
+            <div className="mb-6 p-4 border border-border rounded-lg bg-muted/30">
+              <h3 className="text-sm font-semibold mb-4">{t('add_new')}</h3>
+              <SidebarAppForm
+                onSave={handleCreate}
+                onCancel={() => setIsCreating(false)}
+              />
+            </div>
+          )}
+
+          {/* Add button */}
+          {!isCreating && !editingId && (
+            <Button
+              onClick={() => setIsCreating(true)}
+              className="mb-6 w-full sm:w-auto"
+            >
+              <Plus className="w-4 h-4 mr-2" />
+              {t('add_new')}
+            </Button>
+          )}
+
+          {/* Apps list */}
+          <div className="space-y-3">
+            {sidebarApps.map((app) => {
+              const AppIcon = lucideIcons[app.icon as keyof typeof lucideIcons] as LucideIcon | undefined;
+
+              if (editingId === app.id) {
+                return (
+                  <div key={app.id} className="p-4 border border-border rounded-lg bg-muted/30">
+                    <h3 className="text-sm font-semibold mb-4">{t('edit_app')}</h3>
+                    <SidebarAppForm
+                      app={app}
+                      onSave={(data) => handleUpdate(app.id, data)}
+                      onCancel={() => setEditingId(null)}
+                    />
+                  </div>
+                );
+              }
+
+              return (
+                <div
+                  key={app.id}
+                  className="flex items-center gap-3 p-3 border border-border rounded-lg"
+                >
+                  <div className="flex items-center justify-center w-9 h-9 rounded-md bg-muted">
+                    {AppIcon ? <AppIcon className="w-5 h-5 text-muted-foreground" /> : null}
+                  </div>
+                  <div className="flex-1 min-w-0">
+                    <p className="font-medium text-sm truncate">{app.name}</p>
+                    <p className="text-xs text-muted-foreground truncate">{app.url}</p>
+                  </div>
+                  <span className={cn(
+                    'text-[10px] px-1.5 py-0.5 rounded-full font-medium',
+                    app.openMode === 'inline'
+                      ? 'bg-blue-100 text-blue-700 dark:bg-blue-950/40 dark:text-blue-400'
+                      : 'bg-gray-100 text-gray-700 dark:bg-gray-800 dark:text-gray-400'
+                  )}>
+                    {app.openMode === 'inline' ? t('inline_badge') : t('tab_badge')}
+                  </span>
+                  <div className="flex items-center gap-1">
+                    <Button
+                      variant="ghost"
+                      size="sm"
+                      onClick={() => setEditingId(app.id)}
+                      disabled={!!editingId || isCreating}
+                    >
+                      <Pencil className="w-4 h-4" />
+                    </Button>
+                    <Button
+                      variant="ghost"
+                      size="sm"
+                      onClick={() => handleDelete(app)}
+                      disabled={!!editingId || isCreating}
+                    >
+                      <Trash2 className="w-4 h-4 text-destructive" />
+                    </Button>
+                  </div>
+                </div>
+              );
+            })}
+
+            {sidebarApps.length === 0 && !isCreating && (
+              <div className="text-center py-12 text-muted-foreground">
+                <Plus className="w-12 h-12 mx-auto mb-3 opacity-50" />
+                <p className="text-sm">{t('no_apps')}</p>
+                <p className="text-xs mt-1">{t('no_apps_hint')}</p>
+              </div>
+            )}
+          </div>
+        </div>
+      </div>
+
+      <ConfirmDialog {...confirmDialogProps} />
+    </div>
+  );
+}
diff --git a/components/settings/sidebar-apps-settings.tsx b/components/settings/sidebar-apps-settings.tsx
new file mode 100644
index 00000000..857cff4f
--- /dev/null
+++ b/components/settings/sidebar-apps-settings.tsx
@@ -0,0 +1,280 @@
+"use client";
+
+import { useState, useCallback } from "react";
+import { useTranslations } from "next-intl";
+import { Plus, Pencil, Trash2, ExternalLink, PanelRight, GripVertical } from "lucide-react";
+import { icons as lucideIcons, type LucideIcon } from "lucide-react";
+import { Button } from "@/components/ui/button";
+import { Input } from "@/components/ui/input";
+import { SettingsSection, SettingItem, ToggleSwitch } from "./settings-section";
+import { IconPicker } from "@/components/layout/icon-picker";
+import { useSettingsStore, type SidebarApp } from "@/stores/settings-store";
+import { useConfirmDialog } from "@/hooks/use-confirm-dialog";
+import { ConfirmDialog } from "@/components/ui/confirm-dialog";
+import { cn } from "@/lib/utils";
+
+interface SidebarAppFormData {
+  name: string;
+  url: string;
+  icon: string;
+  openMode: "tab" | "inline";
+}
+
+function AppForm({
+  app,
+  onSave,
+  onCancel,
+}: {
+  app?: SidebarApp;
+  onSave: (data: SidebarAppFormData) => void;
+  onCancel: () => void;
+}) {
+  const t = useTranslations("sidebar_apps");
+  const isEditing = !!app;
+
+  const [formData, setFormData] = useState<SidebarAppFormData>({
+    name: app?.name || "",
+    url: app?.url || "",
+    icon: app?.icon || "Globe",
+    openMode: app?.openMode || "tab",
+  });
+  const [errors, setErrors] = useState<Record<string, string>>({});
+
+  const validate = (): boolean => {
+    const newErrors: Record<string, string> = {};
+    if (!formData.name.trim()) {
+      newErrors.name = t("name_required");
+    }
+    if (!formData.url.trim()) {
+      newErrors.url = t("url_required");
+    } else {
+      try {
+        const parsed = new URL(formData.url);
+        if (!["http:", "https:"].includes(parsed.protocol)) {
+          newErrors.url = t("url_invalid");
+        }
+      } catch {
+        newErrors.url = t("url_invalid");
+      }
+    }
+    if (!formData.icon) {
+      newErrors.icon = t("icon_required");
+    }
+    setErrors(newErrors);
+    return Object.keys(newErrors).length === 0;
+  };
+
+  const handleSubmit = (e: React.FormEvent) => {
+    e.preventDefault();
+    if (!validate()) return;
+    onSave(formData);
+  };
+
+  const SelectedIcon = formData.icon
+    ? (lucideIcons[formData.icon as keyof typeof lucideIcons] as LucideIcon | undefined)
+    : null;
+
+  return (
+    <form onSubmit={handleSubmit} className="space-y-4 p-4 border border-border rounded-lg bg-secondary/30">
+      <div>
+        <label className="text-sm font-medium">{t("name_label")}</label>
+        <Input
+          value={formData.name}
+          onChange={(e) => setFormData({ ...formData, name: e.target.value })}
+          placeholder={t("name_placeholder")}
+          className="mt-1"
+        />
+        {errors.name && <p className="text-xs text-destructive mt-1">{errors.name}</p>}
+      </div>
+
+      <div>
+        <label className="text-sm font-medium">{t("url_label")}</label>
+        <Input
+          value={formData.url}
+          onChange={(e) => setFormData({ ...formData, url: e.target.value })}
+          placeholder="https://example.com"
+          className="mt-1"
+        />
+        {errors.url && <p className="text-xs text-destructive mt-1">{errors.url}</p>}
+      </div>
+
+      <div>
+        <label className="text-sm font-medium block mb-1">{t("icon_label")}</label>
+        <div className="flex items-center gap-2 mb-2">
+          {SelectedIcon && (
+            <div className="w-8 h-8 rounded-md bg-muted flex items-center justify-center">
+              <SelectedIcon className="w-4 h-4" />
+            </div>
+          )}
+          <span className="text-sm text-muted-foreground">{formData.icon}</span>
+        </div>
+        <IconPicker value={formData.icon} onChange={(icon) => setFormData({ ...formData, icon })} />
+        {errors.icon && <p className="text-xs text-destructive mt-1">{errors.icon}</p>}
+      </div>
+
+      <div>
+        <label className="text-sm font-medium block mb-2">{t("open_mode_label")}</label>
+        <div className="flex gap-2">
+          <button
+            type="button"
+            onClick={() => setFormData({ ...formData, openMode: "tab" })}
+            className={cn(
+              "flex items-center gap-2 px-3 py-2 rounded-md text-sm border transition-colors",
+              formData.openMode === "tab"
+                ? "border-primary bg-primary/10 text-primary"
+                : "border-border hover:bg-muted"
+            )}
+          >
+            <ExternalLink className="w-4 h-4" />
+            {t("open_new_tab")}
+          </button>
+          <button
+            type="button"
+            onClick={() => setFormData({ ...formData, openMode: "inline" })}
+            className={cn(
+              "flex items-center gap-2 px-3 py-2 rounded-md text-sm border transition-colors",
+              formData.openMode === "inline"
+                ? "border-primary bg-primary/10 text-primary"
+                : "border-border hover:bg-muted"
+            )}
+          >
+            <PanelRight className="w-4 h-4" />
+            {t("open_inline")}
+          </button>
+        </div>
+      </div>
+
+      <div className="flex gap-2 justify-end">
+        <Button type="button" variant="ghost" size="sm" onClick={onCancel}>
+          {t("cancel")}
+        </Button>
+        <Button type="submit" size="sm">
+          {isEditing ? t("update") : t("add")}
+        </Button>
+      </div>
+    </form>
+  );
+}
+
+export function SidebarAppsSettings() {
+  const t = useTranslations("settings.sidebar_apps");
+  const tApps = useTranslations("sidebar_apps");
+  const { sidebarApps, keepAppsLoaded, addSidebarApp, updateSidebarApp, removeSidebarApp, updateSetting } = useSettingsStore();
+  const [editingApp, setEditingApp] = useState<string | null>(null);
+  const [showAddForm, setShowAddForm] = useState(false);
+  const { dialogProps: confirmDialogProps, confirm: confirmDialog } = useConfirmDialog();
+
+  const handleAdd = useCallback((data: SidebarAppFormData) => {
+    const id = `app-${Date.now()}-${Math.random().toString(36).slice(2, 7)}`;
+    addSidebarApp({ id, ...data });
+    setShowAddForm(false);
+  }, [addSidebarApp]);
+
+  const handleUpdate = useCallback((id: string, data: SidebarAppFormData) => {
+    updateSidebarApp(id, data);
+    setEditingApp(null);
+  }, [updateSidebarApp]);
+
+  const handleDelete = useCallback(async (app: SidebarApp) => {
+    const confirmed = await confirmDialog({
+      title: tApps("delete_confirm_title"),
+      message: tApps("delete_confirm", { name: app.name }),
+      confirmText: tApps("delete"),
+      variant: 'destructive',
+    });
+    if (!confirmed) return;
+    removeSidebarApp(app.id);
+  }, [confirmDialog, tApps, removeSidebarApp]);
+
+  return (
+    <>
+      <SettingsSection title={t("title")} description={t("description")}>
+        <SettingItem label={t("keep_loaded")} description={t("keep_loaded_description")}>
+          <ToggleSwitch
+            checked={keepAppsLoaded}
+            onChange={(v) => updateSetting("keepAppsLoaded", v)}
+          />
+        </SettingItem>
+      </SettingsSection>
+
+      <SettingsSection title={t("manage_title")} description={t("manage_description")}>
+        <div className="space-y-3">
+          {sidebarApps.length === 0 && !showAddForm && (
+            <p className="text-sm text-muted-foreground py-4 text-center">{tApps("no_apps_hint")}</p>
+          )}
+
+          {sidebarApps.map((app) => {
+            if (editingApp === app.id) {
+              return (
+                <AppForm
+                  key={app.id}
+                  app={app}
+                  onSave={(data) => handleUpdate(app.id, data)}
+                  onCancel={() => setEditingApp(null)}
+                />
+              );
+            }
+
+            const AppIcon = lucideIcons[app.icon as keyof typeof lucideIcons] as LucideIcon | undefined;
+            return (
+              <div
+                key={app.id}
+                className="flex items-center gap-3 p-3 border border-border rounded-lg hover:bg-muted/50 transition-colors"
+              >
+                <GripVertical className="w-4 h-4 text-muted-foreground/50 flex-shrink-0" />
+                <div className="w-8 h-8 rounded-md bg-muted flex items-center justify-center flex-shrink-0">
+                  {AppIcon ? <AppIcon className="w-4 h-4" /> : null}
+                </div>
+                <div className="flex-1 min-w-0">
+                  <div className="text-sm font-medium truncate">{app.name}</div>
+                  <div className="text-xs text-muted-foreground truncate">{app.url}</div>
+                </div>
+                <span className={cn(
+                  "text-[10px] px-1.5 py-0.5 rounded-full flex-shrink-0",
+                  app.openMode === "inline"
+                    ? "bg-blue-500/10 text-blue-600 dark:text-blue-400"
+                    : "bg-muted text-muted-foreground"
+                )}>
+                  {app.openMode === "inline" ? tApps("inline_badge") : tApps("tab_badge")}
+                </span>
+                <button
+                  onClick={() => setEditingApp(app.id)}
+                  className="p-1.5 rounded-md hover:bg-muted text-muted-foreground hover:text-foreground transition-colors"
+                >
+                  <Pencil className="w-3.5 h-3.5" />
+                </button>
+                <button
+                  onClick={() => handleDelete(app)}
+                  className="p-1.5 rounded-md hover:bg-destructive/10 text-muted-foreground hover:text-destructive transition-colors"
+                >
+                  <Trash2 className="w-3.5 h-3.5" />
+                </button>
+              </div>
+            );
+          })}
+
+          {showAddForm && (
+            <AppForm
+              onSave={handleAdd}
+              onCancel={() => setShowAddForm(false)}
+            />
+          )}
+
+          {!showAddForm && !editingApp && (
+            <Button
+              variant="outline"
+              size="sm"
+              onClick={() => setShowAddForm(true)}
+              className="w-full"
+            >
+              <Plus className="w-4 h-4 mr-2" />
+              {tApps("add_new")}
+            </Button>
+          )}
+        </div>
+      </SettingsSection>
+
+      <ConfirmDialog {...confirmDialogProps} />
+    </>
+  );
+}
diff --git a/hooks/use-sidebar-apps.ts b/hooks/use-sidebar-apps.ts
new file mode 100644
index 00000000..00ab8ff2
--- /dev/null
+++ b/hooks/use-sidebar-apps.ts
@@ -0,0 +1,49 @@
+import { useState, useCallback } from 'react';
+import { useSettingsStore } from '@/stores/settings-store';
+
+export interface InlineAppState {
+  id: string;
+  url: string;
+  name: string;
+}
+
+export function useSidebarApps() {
+  const [showAppsModal, setShowAppsModal] = useState(false);
+  const [inlineApp, setInlineApp] = useState<InlineAppState | null>(null);
+  const [loadedApps, setLoadedApps] = useState<InlineAppState[]>([]);
+  const keepAppsLoaded = useSettingsStore((s) => s.keepAppsLoaded);
+
+  const handleManageApps = useCallback(() => {
+    setShowAppsModal(true);
+  }, []);
+
+  const handleInlineApp = useCallback((appId: string, url: string, name: string) => {
+    const app = { id: appId, url, name };
+    setInlineApp(app);
+    setLoadedApps((prev) => {
+      if (prev.some((a) => a.id === appId)) return prev;
+      return [...prev, app];
+    });
+  }, []);
+
+  const closeInlineApp = useCallback(() => {
+    if (!keepAppsLoaded) {
+      setLoadedApps((prev) => prev.filter((a) => a.id !== inlineApp?.id));
+    }
+    setInlineApp(null);
+  }, [keepAppsLoaded, inlineApp]);
+
+  const closeAppsModal = useCallback(() => {
+    setShowAppsModal(false);
+  }, []);
+
+  return {
+    showAppsModal,
+    inlineApp,
+    loadedApps: keepAppsLoaded ? loadedApps : (inlineApp ? [inlineApp] : []),
+    handleManageApps,
+    handleInlineApp,
+    closeInlineApp,
+    closeAppsModal,
+  };
+}
diff --git a/locales/de/common.json b/locales/de/common.json
index 23ffc91c..0734ead9 100644
--- a/locales/de/common.json
+++ b/locales/de/common.json
@@ -98,7 +98,38 @@
     "vacation_active": "Abwesenheitsnotiz ist aktiv",
     "tags": "Tags",
     "mail": "E-Mail",
-    "nav_label": "Navigation"
+    "nav_label": "Navigation",
+    "add_app": "Apps"
+  },
+  "sidebar_apps": {
+    "modal_title": "Sidebar-Apps",
+    "add_new": "App hinzufügen",
+    "edit_app": "App bearbeiten",
+    "name_label": "Name",
+    "name_placeholder": "Meine App",
+    "name_required": "Name ist erforderlich",
+    "url_label": "URL",
+    "url_required": "URL ist erforderlich",
+    "url_invalid": "Geben Sie eine gültige http- oder https-URL ein",
+    "icon_label": "Symbol",
+    "icon_required": "Symbol ist erforderlich",
+    "open_mode_label": "Öffnungsmodus",
+    "open_new_tab": "Neuer Tab",
+    "open_inline": "Eingebettet",
+    "cancel": "Abbrechen",
+    "add": "Hinzufügen",
+    "update": "Aktualisieren",
+    "delete": "Löschen",
+    "delete_confirm_title": "App löschen",
+    "delete_confirm": "Möchten Sie \"{name}\" wirklich löschen?",
+    "no_apps": "Noch keine Apps hinzugefügt",
+    "no_apps_hint": "Fügen Sie benutzerdefinierte Apps und Links zur Seitenleiste hinzu",
+    "search_icons": "Symbole suchen...",
+    "show_popular": "Beliebt",
+    "show_all": "Alle",
+    "no_icons_found": "Keine Symbole gefunden",
+    "inline_badge": "Eingebettet",
+    "tab_badge": "Tab"
   },
   "email_list": {
     "no_emails": "Keine Nachrichten gefunden",
@@ -563,7 +594,8 @@
       "security": "Sicherheit",
       "encryption": "Verschlüsselung",
       "files": "Dateien",
-      "contacts": "Contacts"
+      "contacts": "Contacts",
+      "sidebar_apps": "Sidebar-Apps"
     },
     "tab_groups": {
       "general": "Allgemein",
@@ -1004,6 +1036,14 @@
         "button": "Importieren"
       }
     },
+    "sidebar_apps": {
+      "title": "Sidebar-Apps",
+      "description": "Benutzerdefinierte Apps und Links in der Seitenleiste verwalten",
+      "keep_loaded": "Apps geladen halten",
+      "keep_loaded_description": "Inline-Apps beim Wechsel im Hintergrund laufen lassen, um Neuladen zu vermeiden",
+      "manage_title": "Benutzerdefinierte Apps",
+      "manage_description": "Apps in der Seitenleiste hinzufügen, bearbeiten oder entfernen"
+    },
     "contacts": {
       "title": "Contacts",
       "description": "Import and export your contacts",
diff --git a/locales/en/common.json b/locales/en/common.json
index 37894881..e3883602 100644
--- a/locales/en/common.json
+++ b/locales/en/common.json
@@ -98,7 +98,38 @@
     "vacation_active": "Vacation responder is active",
     "tags": "Tags",
     "mail": "Mail",
-    "nav_label": "Navigation"
+    "nav_label": "Navigation",
+    "add_app": "Apps"
+  },
+  "sidebar_apps": {
+    "modal_title": "Sidebar Apps",
+    "add_new": "Add App",
+    "edit_app": "Edit App",
+    "name_label": "Name",
+    "name_placeholder": "My App",
+    "name_required": "Name is required",
+    "url_label": "URL",
+    "url_required": "URL is required",
+    "url_invalid": "Enter a valid http or https URL",
+    "icon_label": "Icon",
+    "icon_required": "Icon is required",
+    "open_mode_label": "Open Mode",
+    "open_new_tab": "New Tab",
+    "open_inline": "Inline",
+    "cancel": "Cancel",
+    "add": "Add",
+    "update": "Update",
+    "delete": "Delete",
+    "delete_confirm_title": "Delete App",
+    "delete_confirm": "Are you sure you want to delete \"{name}\"?",
+    "no_apps": "No apps added yet",
+    "no_apps_hint": "Add custom apps and links to your sidebar",
+    "search_icons": "Search icons...",
+    "show_popular": "Popular",
+    "show_all": "All",
+    "no_icons_found": "No icons found",
+    "inline_badge": "Inline",
+    "tab_badge": "Tab"
   },
   "email_list": {
     "no_emails": "No messages found",
@@ -563,7 +594,8 @@
       "security": "Security",
       "files": "Files",
       "contacts": "Contacts",
-      "encryption": "Encryption"
+      "encryption": "Encryption",
+      "sidebar_apps": "Sidebar Apps"
     },
     "tab_groups": {
       "general": "General",
@@ -1004,6 +1036,14 @@
         "button": "Import"
       }
     },
+    "sidebar_apps": {
+      "title": "Sidebar Apps",
+      "description": "Manage custom apps and links in your sidebar",
+      "keep_loaded": "Keep Apps Loaded",
+      "keep_loaded_description": "Keep inline apps running in the background when switching between them to avoid reloading",
+      "manage_title": "Custom Apps",
+      "manage_description": "Add, edit, or remove custom apps from your sidebar"
+    },
     "contacts": {
       "title": "Contacts",
       "description": "Import and export your contacts",
diff --git a/locales/es/common.json b/locales/es/common.json
index 0446f23b..0213bb17 100644
--- a/locales/es/common.json
+++ b/locales/es/common.json
@@ -98,7 +98,38 @@
     "vacation_active": "Respuesta automática activa",
     "tags": "Etiquetas",
     "mail": "Correo",
-    "nav_label": "Navegación"
+    "nav_label": "Navegación",
+    "add_app": "Apps"
+  },
+  "sidebar_apps": {
+    "modal_title": "Aplicaciones de la barra lateral",
+    "add_new": "Añadir aplicación",
+    "edit_app": "Editar aplicación",
+    "name_label": "Nombre",
+    "name_placeholder": "Mi aplicación",
+    "name_required": "El nombre es obligatorio",
+    "url_label": "URL",
+    "url_required": "La URL es obligatoria",
+    "url_invalid": "Introduce una URL http o https válida",
+    "icon_label": "Icono",
+    "icon_required": "El icono es obligatorio",
+    "open_mode_label": "Modo de apertura",
+    "open_new_tab": "Nueva pestaña",
+    "open_inline": "Integrado",
+    "cancel": "Cancelar",
+    "add": "Añadir",
+    "update": "Actualizar",
+    "delete": "Eliminar",
+    "delete_confirm_title": "Eliminar aplicación",
+    "delete_confirm": "¿Estás seguro de que quieres eliminar \"{name}\"?",
+    "no_apps": "No se han añadido aplicaciones",
+    "no_apps_hint": "Añade aplicaciones y enlaces personalizados a tu barra lateral",
+    "search_icons": "Buscar iconos...",
+    "show_popular": "Populares",
+    "show_all": "Todos",
+    "no_icons_found": "No se encontraron iconos",
+    "inline_badge": "Integrado",
+    "tab_badge": "Pestaña"
   },
   "email_list": {
     "no_emails": "No se encontraron mensajes",
@@ -563,7 +594,8 @@
       "security": "Seguridad",
       "encryption": "Cifrado",
       "files": "Archivos",
-      "contacts": "Contacts"
+      "contacts": "Contacts",
+      "sidebar_apps": "Apps de barra lateral"
     },
     "tab_groups": {
       "general": "General",
@@ -1004,6 +1036,14 @@
         "button": "Importar"
       }
     },
+    "sidebar_apps": {
+      "title": "Apps de barra lateral",
+      "description": "Gestionar aplicaciones y enlaces personalizados en la barra lateral",
+      "keep_loaded": "Mantener apps cargadas",
+      "keep_loaded_description": "Mantener las apps en línea ejecutándose en segundo plano al cambiar entre ellas para evitar recargas",
+      "manage_title": "Apps personalizadas",
+      "manage_description": "Agregar, editar o eliminar apps personalizadas de la barra lateral"
+    },
     "contacts": {
       "title": "Contacts",
       "description": "Import and export your contacts",
diff --git a/locales/fr/common.json b/locales/fr/common.json
index 013c9f00..51cfc93b 100644
--- a/locales/fr/common.json
+++ b/locales/fr/common.json
@@ -98,7 +98,38 @@
     "vacation_active": "Répondeur d'absence activé",
     "tags": "Étiquettes",
     "mail": "Messagerie",
-    "nav_label": "Navigation"
+    "nav_label": "Navigation",
+    "add_app": "Apps"
+  },
+  "sidebar_apps": {
+    "modal_title": "Applications de la barre latérale",
+    "add_new": "Ajouter une application",
+    "edit_app": "Modifier l'application",
+    "name_label": "Nom",
+    "name_placeholder": "Mon application",
+    "name_required": "Le nom est requis",
+    "url_label": "URL",
+    "url_required": "L'URL est requise",
+    "url_invalid": "Entrez une URL http ou https valide",
+    "icon_label": "Icône",
+    "icon_required": "L'icône est requise",
+    "open_mode_label": "Mode d'ouverture",
+    "open_new_tab": "Nouvel onglet",
+    "open_inline": "Intégré",
+    "cancel": "Annuler",
+    "add": "Ajouter",
+    "update": "Mettre à jour",
+    "delete": "Supprimer",
+    "delete_confirm_title": "Supprimer l'application",
+    "delete_confirm": "Êtes-vous sûr de vouloir supprimer \"{name}\" ?",
+    "no_apps": "Aucune application ajoutée",
+    "no_apps_hint": "Ajoutez des applications et liens personnalisés à votre barre latérale",
+    "search_icons": "Rechercher des icônes...",
+    "show_popular": "Populaires",
+    "show_all": "Toutes",
+    "no_icons_found": "Aucune icône trouvée",
+    "inline_badge": "Intégré",
+    "tab_badge": "Onglet"
   },
   "email_list": {
     "no_emails": "Aucun message trouvé",
@@ -563,7 +594,8 @@
       "security": "Sécurité",
       "encryption": "Chiffrement",
       "files": "Fichiers",
-      "contacts": "Contacts"
+      "contacts": "Contacts",
+      "sidebar_apps": "Apps de la barre latérale"
     },
     "tab_groups": {
       "general": "Général",
@@ -1004,6 +1036,14 @@
         "button": "Importer"
       }
     },
+    "sidebar_apps": {
+      "title": "Apps de la barre latérale",
+      "description": "Gérer les applications et liens personnalisés dans la barre latérale",
+      "keep_loaded": "Garder les apps chargées",
+      "keep_loaded_description": "Garder les apps en ligne en arrière-plan lors du basculement pour éviter le rechargement",
+      "manage_title": "Apps personnalisées",
+      "manage_description": "Ajouter, modifier ou supprimer des apps personnalisées de la barre latérale"
+    },
     "contacts": {
       "title": "Contacts",
       "description": "Import and export your contacts",
diff --git a/locales/it/common.json b/locales/it/common.json
index bc77dc7c..010eec90 100644
--- a/locales/it/common.json
+++ b/locales/it/common.json
@@ -98,7 +98,38 @@
     "vacation_active": "Risponditore automatico attivo",
     "tags": "Etichette",
     "mail": "Posta",
-    "nav_label": "Navigazione"
+    "nav_label": "Navigazione",
+    "add_app": "App"
+  },
+  "sidebar_apps": {
+    "modal_title": "App della barra laterale",
+    "add_new": "Aggiungi app",
+    "edit_app": "Modifica app",
+    "name_label": "Nome",
+    "name_placeholder": "La mia app",
+    "name_required": "Il nome è obbligatorio",
+    "url_label": "URL",
+    "url_required": "L'URL è obbligatorio",
+    "url_invalid": "Inserisci un URL http o https valido",
+    "icon_label": "Icona",
+    "icon_required": "L'icona è obbligatoria",
+    "open_mode_label": "Modalità di apertura",
+    "open_new_tab": "Nuova scheda",
+    "open_inline": "Integrato",
+    "cancel": "Annulla",
+    "add": "Aggiungi",
+    "update": "Aggiorna",
+    "delete": "Elimina",
+    "delete_confirm_title": "Elimina app",
+    "delete_confirm": "Sei sicuro di voler eliminare \"{name}\"?",
+    "no_apps": "Nessuna app aggiunta",
+    "no_apps_hint": "Aggiungi app e link personalizzati alla barra laterale",
+    "search_icons": "Cerca icone...",
+    "show_popular": "Popolari",
+    "show_all": "Tutte",
+    "no_icons_found": "Nessuna icona trovata",
+    "inline_badge": "Integrato",
+    "tab_badge": "Scheda"
   },
   "email_list": {
     "no_emails": "Nessun messaggio trovato",
@@ -563,7 +594,8 @@
       "security": "Sicurezza",
       "encryption": "Cifratura",
       "files": "File",
-      "contacts": "Contacts"
+      "contacts": "Contacts",
+      "sidebar_apps": "App nella barra laterale"
     },
     "tab_groups": {
       "general": "Generale",
@@ -1004,6 +1036,14 @@
         "button": "Importa"
       }
     },
+    "sidebar_apps": {
+      "title": "App nella barra laterale",
+      "description": "Gestisci app e link personalizzati nella barra laterale",
+      "keep_loaded": "Mantieni app caricate",
+      "keep_loaded_description": "Mantieni le app inline in esecuzione in background durante il passaggio per evitare il ricaricamento",
+      "manage_title": "App personalizzate",
+      "manage_description": "Aggiungi, modifica o rimuovi app personalizzate dalla barra laterale"
+    },
     "contacts": {
       "title": "Contacts",
       "description": "Import and export your contacts",
diff --git a/locales/ja/common.json b/locales/ja/common.json
index 11b5b179..7d1fd31d 100644
--- a/locales/ja/common.json
+++ b/locales/ja/common.json
@@ -98,7 +98,38 @@
     "vacation_active": "不在応答が有効です",
     "tags": "タグ",
     "mail": "メール",
-    "nav_label": "ナビゲーション"
+    "nav_label": "ナビゲーション",
+    "add_app": "アプリ"
+  },
+  "sidebar_apps": {
+    "modal_title": "サイドバーアプリ",
+    "add_new": "アプリを追加",
+    "edit_app": "アプリを編集",
+    "name_label": "名前",
+    "name_placeholder": "マイアプリ",
+    "name_required": "名前は必須です",
+    "url_label": "URL",
+    "url_required": "URLは必須です",
+    "url_invalid": "有効なhttpまたはhttps URLを入力してください",
+    "icon_label": "アイコン",
+    "icon_required": "アイコンは必須です",
+    "open_mode_label": "開き方",
+    "open_new_tab": "新しいタブ",
+    "open_inline": "埋め込み",
+    "cancel": "キャンセル",
+    "add": "追加",
+    "update": "更新",
+    "delete": "削除",
+    "delete_confirm_title": "アプリを削除",
+    "delete_confirm": "「{name}」を削除してもよろしいですか？",
+    "no_apps": "アプリが追加されていません",
+    "no_apps_hint": "カスタムアプリやリンクをサイドバーに追加できます",
+    "search_icons": "アイコンを検索...",
+    "show_popular": "人気",
+    "show_all": "すべて",
+    "no_icons_found": "アイコンが見つかりません",
+    "inline_badge": "埋め込み",
+    "tab_badge": "タブ"
   },
   "email_list": {
     "no_emails": "メッセージが見つかりません",
@@ -563,7 +594,8 @@
       "security": "セキュリティ",
       "encryption": "暗号化",
       "files": "ファイル",
-      "contacts": "Contacts"
+      "contacts": "Contacts",
+      "sidebar_apps": "サイドバーアプリ"
     },
     "tab_groups": {
       "general": "一般",
@@ -1004,6 +1036,14 @@
         "button": "インポート"
       }
     },
+    "sidebar_apps": {
+      "title": "サイドバーアプリ",
+      "description": "サイドバーのカスタムアプリとリンクを管理",
+      "keep_loaded": "アプリを読み込んだまま保持",
+      "keep_loaded_description": "切り替え時にインラインアプリをバックグラウンドで実行し続けて再読み込みを回避",
+      "manage_title": "カスタムアプリ",
+      "manage_description": "サイドバーのカスタムアプリを追加、編集、削除"
+    },
     "contacts": {
       "title": "Contacts",
       "description": "Import and export your contacts",
diff --git a/locales/nl/common.json b/locales/nl/common.json
index e2084b88..775bf993 100644
--- a/locales/nl/common.json
+++ b/locales/nl/common.json
@@ -98,7 +98,38 @@
     "vacation_active": "Afwezigheidsmelder is actief",
     "tags": "Labels",
     "mail": "E-mail",
-    "nav_label": "Navigatie"
+    "nav_label": "Navigatie",
+    "add_app": "Apps"
+  },
+  "sidebar_apps": {
+    "modal_title": "Zijbalk-apps",
+    "add_new": "App toevoegen",
+    "edit_app": "App bewerken",
+    "name_label": "Naam",
+    "name_placeholder": "Mijn app",
+    "name_required": "Naam is vereist",
+    "url_label": "URL",
+    "url_required": "URL is vereist",
+    "url_invalid": "Voer een geldige http- of https-URL in",
+    "icon_label": "Pictogram",
+    "icon_required": "Pictogram is vereist",
+    "open_mode_label": "Openingsmodus",
+    "open_new_tab": "Nieuw tabblad",
+    "open_inline": "Ingesloten",
+    "cancel": "Annuleren",
+    "add": "Toevoegen",
+    "update": "Bijwerken",
+    "delete": "Verwijderen",
+    "delete_confirm_title": "App verwijderen",
+    "delete_confirm": "Weet je zeker dat je \"{name}\" wilt verwijderen?",
+    "no_apps": "Nog geen apps toegevoegd",
+    "no_apps_hint": "Voeg aangepaste apps en links toe aan je zijbalk",
+    "search_icons": "Pictogrammen zoeken...",
+    "show_popular": "Populair",
+    "show_all": "Alle",
+    "no_icons_found": "Geen pictogrammen gevonden",
+    "inline_badge": "Ingesloten",
+    "tab_badge": "Tabblad"
   },
   "email_list": {
     "no_emails": "Geen berichten gevonden",
@@ -563,7 +594,8 @@
       "security": "Beveiliging",
       "encryption": "Versleuteling",
       "files": "Bestanden",
-      "contacts": "Contacts"
+      "contacts": "Contacts",
+      "sidebar_apps": "Zijbalk-apps"
     },
     "tab_groups": {
       "general": "Algemeen",
@@ -1004,6 +1036,14 @@
         "button": "Importeren"
       }
     },
+    "sidebar_apps": {
+      "title": "Zijbalk-apps",
+      "description": "Aangepaste apps en links in de zijbalk beheren",
+      "keep_loaded": "Apps geladen houden",
+      "keep_loaded_description": "Inline-apps op de achtergrond laten draaien bij het wisselen om herladen te voorkomen",
+      "manage_title": "Aangepaste apps",
+      "manage_description": "Aangepaste apps toevoegen, bewerken of verwijderen uit de zijbalk"
+    },
     "contacts": {
       "title": "Contacts",
       "description": "Import and export your contacts",
diff --git a/locales/pt/common.json b/locales/pt/common.json
index 65a81660..accd419a 100644
--- a/locales/pt/common.json
+++ b/locales/pt/common.json
@@ -98,7 +98,38 @@
     "vacation_active": "Resposta automática ativa",
     "tags": "Etiquetas",
     "mail": "E-mail",
-    "nav_label": "Navegação"
+    "nav_label": "Navegação",
+    "add_app": "Apps"
+  },
+  "sidebar_apps": {
+    "modal_title": "Apps da barra lateral",
+    "add_new": "Adicionar app",
+    "edit_app": "Editar app",
+    "name_label": "Nome",
+    "name_placeholder": "Meu app",
+    "name_required": "Nome é obrigatório",
+    "url_label": "URL",
+    "url_required": "URL é obrigatório",
+    "url_invalid": "Insira uma URL http ou https válida",
+    "icon_label": "Ícone",
+    "icon_required": "Ícone é obrigatório",
+    "open_mode_label": "Modo de abertura",
+    "open_new_tab": "Nova aba",
+    "open_inline": "Integrado",
+    "cancel": "Cancelar",
+    "add": "Adicionar",
+    "update": "Atualizar",
+    "delete": "Excluir",
+    "delete_confirm_title": "Excluir app",
+    "delete_confirm": "Tem certeza de que deseja excluir \"{name}\"?",
+    "no_apps": "Nenhum app adicionado",
+    "no_apps_hint": "Adicione apps e links personalizados à sua barra lateral",
+    "search_icons": "Pesquisar ícones...",
+    "show_popular": "Populares",
+    "show_all": "Todos",
+    "no_icons_found": "Nenhum ícone encontrado",
+    "inline_badge": "Integrado",
+    "tab_badge": "Aba"
   },
   "email_list": {
     "no_emails": "Nenhuma mensagem encontrada",
@@ -563,7 +594,8 @@
       "security": "Segurança",
       "encryption": "Criptografia",
       "files": "Arquivos",
-      "contacts": "Contacts"
+      "contacts": "Contacts",
+      "sidebar_apps": "Apps da barra lateral"
     },
     "tab_groups": {
       "general": "Geral",
@@ -1004,6 +1036,14 @@
         "button": "Importar"
       }
     },
+    "sidebar_apps": {
+      "title": "Apps da barra lateral",
+      "description": "Gerenciar aplicativos e links personalizados na barra lateral",
+      "keep_loaded": "Manter apps carregados",
+      "keep_loaded_description": "Manter apps inline em execução em segundo plano ao alternar entre eles para evitar recarregamento",
+      "manage_title": "Apps personalizados",
+      "manage_description": "Adicionar, editar ou remover apps personalizados da barra lateral"
+    },
     "contacts": {
       "title": "Contacts",
       "description": "Import and export your contacts",
diff --git a/stores/settings-store.ts b/stores/settings-store.ts
index 9f0f527a..95c3952f 100644
--- a/stores/settings-store.ts
+++ b/stores/settings-store.ts
@@ -38,6 +38,14 @@ export interface KeywordDefinition {
   color: string;  // Key from KEYWORD_PALETTE
 }
 
+export interface SidebarApp {
+  id: string;
+  name: string;
+  url: string;
+  icon: string;       // Lucide icon name (e.g. 'Globe', 'Rss')
+  openMode: 'tab' | 'inline'; // Open in new tab or embed inline
+}
+
 // Available color palette for keywords
 export const KEYWORD_PALETTE: Record<string, { dot: string; bg: string }> = {
   red: { dot: 'bg-red-500', bg: 'bg-red-50 dark:bg-red-950/30' },
@@ -113,6 +121,11 @@ interface SettingsState {
 
   // Keywords (labels/tags)
   emailKeywords: KeywordDefinition[];
+
+  // Sidebar Apps
+  sidebarApps: SidebarApp[];
+  keepAppsLoaded: boolean;
+
   // Advanced
   debugMode: boolean;
   settingsSyncDisabled: boolean;
@@ -142,6 +155,12 @@ interface SettingsState {
   reorderKeywords: (keywords: KeywordDefinition[]) => void;
   getKeywordById: (id: string) => KeywordDefinition | undefined;
 
+  // Sidebar Apps
+  addSidebarApp: (app: SidebarApp) => void;
+  updateSidebarApp: (id: string, updates: Partial<Omit<SidebarApp, 'id'>>) => void;
+  removeSidebarApp: (id: string) => void;
+  reorderSidebarApps: (apps: SidebarApp[]) => void;
+
   // Settings sync
   enableSync: (username: string, serverUrl: string) => void;
   disableSync: () => void;
@@ -197,6 +216,10 @@ const DEFAULT_SETTINGS = {
   // Keywords
   emailKeywords: DEFAULT_KEYWORDS,
 
+  // Sidebar Apps
+  sidebarApps: [] as SidebarApp[],
+  keepAppsLoaded: false,
+
   // Advanced
   debugMode: false,
   settingsSyncDisabled: false,
@@ -261,6 +284,8 @@ export const useSettingsStore = create<SettingsState>()(
           senderFavicons: state.senderFavicons,
           folderIcons: state.folderIcons,
           emailKeywords: state.emailKeywords,
+          sidebarApps: state.sidebarApps,
+          keepAppsLoaded: state.keepAppsLoaded,
           debugMode: state.debugMode,
           settingsSyncDisabled: state.settingsSyncDisabled,
           // Cross-store settings
@@ -364,6 +389,29 @@ export const useSettingsStore = create<SettingsState>()(
         return get().emailKeywords.find(k => k.id === id);
       },
 
+      // Sidebar Apps methods
+      addSidebarApp: (app: SidebarApp) => {
+        const current = get().sidebarApps;
+        if (current.some(a => a.id === app.id)) return;
+        set({ sidebarApps: [...current, app] });
+      },
+
+      updateSidebarApp: (id: string, updates: Partial<Omit<SidebarApp, 'id'>>) => {
+        set({
+          sidebarApps: get().sidebarApps.map(a =>
+            a.id === id ? { ...a, ...updates } : a
+          ),
+        });
+      },
+
+      removeSidebarApp: (id: string) => {
+        set({ sidebarApps: get().sidebarApps.filter(a => a.id !== id) });
+      },
+
+      reorderSidebarApps: (apps: SidebarApp[]) => {
+        set({ sidebarApps: apps });
+      },
+
       // Settings sync methods
       enableSync: (username: string, serverUrl: string) => {
         syncUsername = username;