diff --git a/app/api/notifications/[id]/read/route.ts b/app/api/notifications/[id]/read/route.ts
new file mode 100644
index 00000000..a97c3e2d
--- /dev/null
+++ b/app/api/notifications/[id]/read/route.ts
@@ -0,0 +1,50 @@
+import { NextResponse } from 'next/server';
+import { getServerSession } from 'next-auth';
+import { authOptions } from '@/app/api/auth/[...nextauth]/route';
+import { NotificationService } from '@/lib/services/notifications/notification-service';
+
+// POST /api/notifications/{id}/read
+export async function POST(
+  request: Request,
+  context: { params: { id: string } }
+) {
+  try {
+    // Authenticate user
+    const session = await getServerSession(authOptions);
+    if (!session || !session.user?.id) {
+      return NextResponse.json(
+        { error: "Not authenticated" },
+        { status: 401 }
+      );
+    }
+
+    // Await params as per Next.js requirements
+    const params = await context.params;
+    const id = params?.id;
+    if (!id) {
+      return NextResponse.json(
+        { error: "Missing notification ID" },
+        { status: 400 }
+      );
+    }
+
+    const userId = session.user.id;
+    const notificationService = NotificationService.getInstance();
+    const success = await notificationService.markAsRead(userId, id);
+    
+    if (!success) {
+      return NextResponse.json(
+        { error: "Failed to mark notification as read" },
+        { status: 400 }
+      );
+    }
+    
+    return NextResponse.json({ success: true });
+  } catch (error: any) {
+    console.error('Error marking notification as read:', error);
+    return NextResponse.json(
+      { error: "Internal server error", message: error.message },
+      { status: 500 }
+    );
+  }
+} 
\ No newline at end of file
diff --git a/app/api/notifications/count/route.ts b/app/api/notifications/count/route.ts
new file mode 100644
index 00000000..f769d359
--- /dev/null
+++ b/app/api/notifications/count/route.ts
@@ -0,0 +1,30 @@
+import { NextResponse } from 'next/server';
+import { getServerSession } from 'next-auth';
+import { authOptions } from '@/app/api/auth/[...nextauth]/route';
+import { NotificationService } from '@/lib/services/notifications/notification-service';
+
+// GET /api/notifications/count
+export async function GET(request: Request) {
+  try {
+    // Authenticate user
+    const session = await getServerSession(authOptions);
+    if (!session || !session.user?.id) {
+      return NextResponse.json(
+        { error: "Not authenticated" },
+        { status: 401 }
+      );
+    }
+
+    const userId = session.user.id;
+    const notificationService = NotificationService.getInstance();
+    const counts = await notificationService.getNotificationCount(userId);
+    
+    return NextResponse.json(counts);
+  } catch (error: any) {
+    console.error('Error in notification count API:', error);
+    return NextResponse.json(
+      { error: "Internal server error", message: error.message },
+      { status: 500 }
+    );
+  }
+} 
\ No newline at end of file
diff --git a/app/api/notifications/read-all/route.ts b/app/api/notifications/read-all/route.ts
new file mode 100644
index 00000000..bcee46cf
--- /dev/null
+++ b/app/api/notifications/read-all/route.ts
@@ -0,0 +1,37 @@
+import { NextResponse } from 'next/server';
+import { getServerSession } from 'next-auth';
+import { authOptions } from '@/app/api/auth/[...nextauth]/route';
+import { NotificationService } from '@/lib/services/notifications/notification-service';
+
+// POST /api/notifications/read-all
+export async function POST(request: Request) {
+  try {
+    // Authenticate user
+    const session = await getServerSession(authOptions);
+    if (!session || !session.user?.id) {
+      return NextResponse.json(
+        { error: "Not authenticated" },
+        { status: 401 }
+      );
+    }
+
+    const userId = session.user.id;
+    const notificationService = NotificationService.getInstance();
+    const success = await notificationService.markAllAsRead(userId);
+    
+    if (!success) {
+      return NextResponse.json(
+        { error: "Failed to mark all notifications as read" },
+        { status: 400 }
+      );
+    }
+    
+    return NextResponse.json({ success: true });
+  } catch (error: any) {
+    console.error('Error marking all notifications as read:', error);
+    return NextResponse.json(
+      { error: "Internal server error", message: error.message },
+      { status: 500 }
+    );
+  }
+} 
\ No newline at end of file
diff --git a/app/api/notifications/route.ts b/app/api/notifications/route.ts
new file mode 100644
index 00000000..a9b405ad
--- /dev/null
+++ b/app/api/notifications/route.ts
@@ -0,0 +1,54 @@
+import { NextResponse } from 'next/server';
+import { getServerSession } from 'next-auth';
+import { authOptions } from '@/app/api/auth/[...nextauth]/route';
+import { NotificationService } from '@/lib/services/notifications/notification-service';
+
+// GET /api/notifications?page=1&limit=20
+export async function GET(request: Request) {
+  try {
+    // Authenticate user
+    const session = await getServerSession(authOptions);
+    if (!session || !session.user?.id) {
+      return NextResponse.json(
+        { error: "Not authenticated" },
+        { status: 401 }
+      );
+    }
+
+    const userId = session.user.id;
+    const { searchParams } = new URL(request.url);
+    const page = parseInt(searchParams.get('page') || '1', 10);
+    const limit = parseInt(searchParams.get('limit') || '20', 10);
+    
+    // Validate parameters
+    if (isNaN(page) || page < 1) {
+      return NextResponse.json(
+        { error: "Invalid page parameter" },
+        { status: 400 }
+      );
+    }
+    
+    if (isNaN(limit) || limit < 1 || limit > 100) {
+      return NextResponse.json(
+        { error: "Invalid limit parameter, must be between 1 and 100" },
+        { status: 400 }
+      );
+    }
+    
+    const notificationService = NotificationService.getInstance();
+    const notifications = await notificationService.getNotifications(userId, page, limit);
+    
+    return NextResponse.json({
+      notifications,
+      page,
+      limit,
+      total: notifications.length
+    });
+  } catch (error: any) {
+    console.error('Error in notifications API:', error);
+    return NextResponse.json(
+      { error: "Internal server error", message: error.message },
+      { status: 500 }
+    );
+  }
+} 
\ No newline at end of file
diff --git a/app/notifications/page.tsx b/app/notifications/page.tsx
index 01128ab9..d6084b2b 100644
--- a/app/notifications/page.tsx
+++ b/app/notifications/page.tsx
@@ -1,13 +1,186 @@
+"use client";
+
+import { useEffect, useState } from 'react';
+import { useNotifications } from '@/hooks/use-notifications';
+import { Button } from '@/components/ui/button';
+import { Card, CardContent, CardDescription, CardFooter, CardHeader, CardTitle } from '@/components/ui/card';
+import { Tabs, TabsContent, TabsList, TabsTrigger } from '@/components/ui/tabs';
+import { Notification } from '@/lib/types/notification';
+import { Badge } from '@/components/ui/badge';
+import { formatDistanceToNow } from 'date-fns';
+import { Bell, Check, CheckCheck, ExternalLink, Trash2 } from 'lucide-react';
+import Link from 'next/link';
+
+// Source icon mapping
+const SourceIcons: Record<string, React.ReactNode> = {
+  leantime: <div className="w-8 h-8 rounded-full bg-blue-100 flex items-center justify-center text-blue-600">L</div>,
+  nextcloud: <div className="w-8 h-8 rounded-full bg-blue-100 flex items-center justify-center text-blue-600">N</div>,
+  gitea: <div className="w-8 h-8 rounded-full bg-green-100 flex items-center justify-center text-green-600">G</div>,
+  dolibarr: <div className="w-8 h-8 rounded-full bg-purple-100 flex items-center justify-center text-purple-600">D</div>,
+  moodle: <div className="w-8 h-8 rounded-full bg-orange-100 flex items-center justify-center text-orange-600">M</div>,
+};
+
 export default function NotificationsPage() {
+  const { notifications, notificationCount, loading, error, fetchNotifications, markAsRead, markAllAsRead } = useNotifications();
+  const [activeTab, setActiveTab] = useState('all');
+  
+  // Filter notifications based on active tab
+  const filteredNotifications = activeTab === 'all' 
+    ? notifications 
+    : notifications.filter(notification => notification.source === activeTab);
+  
+  // Group notifications by source for counts
+  const sourceCounts = Object.entries(notificationCount.sources).map(([source, count]) => ({
+    source,
+    count: count.total,
+    unread: count.unread
+  }));
+  
+  const handleMarkAsRead = async (notification: Notification) => {
+    if (!notification.isRead) {
+      await markAsRead(notification.id);
+    }
+  };
+  
+  const handleMarkAllAsRead = async () => {
+    await markAllAsRead();
+  };
+
   return (
-    <div className="w-full h-[calc(100vh-8rem)]">
-      <iframe 
-        src="https://example.com/notifications"
-        className="w-full h-full border-none"
-        allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture"
-        allowFullScreen
-      />
+    <div className="container mx-auto py-6">
+      <div className="flex items-center justify-between mb-6">
+        <div>
+          <h1 className="text-2xl font-bold tracking-tight">Notifications</h1>
+          <p className="text-muted-foreground">
+            Manage your notifications from all connected services
+          </p>
+        </div>
+        <Button variant="outline" onClick={handleMarkAllAsRead} disabled={notificationCount.unread === 0}>
+          <CheckCheck className="mr-2 h-4 w-4" />
+          Mark all as read
+        </Button>
+      </div>
+
+      <Tabs defaultValue="all" value={activeTab} onValueChange={setActiveTab}>
+        <div className="flex justify-between items-center mb-4">
+          <TabsList>
+            <TabsTrigger value="all" className="relative">
+              All
+              {notificationCount.unread > 0 && (
+                <Badge variant="secondary" className="ml-2">
+                  {notificationCount.unread}
+                </Badge>
+              )}
+            </TabsTrigger>
+            
+            {sourceCounts.map(({ source, unread }) => (
+              <TabsTrigger key={source} value={source} className="relative capitalize">
+                {source}
+                {unread > 0 && (
+                  <Badge variant="secondary" className="ml-2">
+                    {unread}
+                  </Badge>
+                )}
+              </TabsTrigger>
+            ))}
+          </TabsList>
+        </div>
+
+        <TabsContent value={activeTab} className="space-y-4">
+          {loading ? (
+            <Card>
+              <CardContent className="py-10 text-center">
+                <div className="flex flex-col items-center">
+                  <div className="animate-spin rounded-full h-8 w-8 border-b-2 border-gray-900 mb-2"></div>
+                  <p>Loading notifications...</p>
+                </div>
+              </CardContent>
+            </Card>
+          ) : error ? (
+            <Card>
+              <CardContent className="py-10 text-center">
+                <div className="flex flex-col items-center">
+                  <p className="text-red-500">{error}</p>
+                  <Button 
+                    variant="outline" 
+                    onClick={() => fetchNotifications()} 
+                    className="mt-4"
+                  >
+                    Retry
+                  </Button>
+                </div>
+              </CardContent>
+            </Card>
+          ) : filteredNotifications.length === 0 ? (
+            <Card>
+              <CardContent className="py-10 text-center">
+                <div className="flex flex-col items-center">
+                  <Bell className="h-12 w-12 text-gray-400 mb-4" />
+                  <h3 className="font-medium text-lg">No notifications</h3>
+                  <p className="text-muted-foreground">
+                    You don't have any {activeTab !== 'all' ? `${activeTab} ` : ''}notifications right now.
+                  </p>
+                </div>
+              </CardContent>
+            </Card>
+          ) : (
+            filteredNotifications.map((notification) => (
+              <Card 
+                key={notification.id}
+                className={notification.isRead ? 'bg-white' : 'bg-blue-50 border-blue-200'}
+              >
+                <CardContent className="p-4">
+                  <div className="flex">
+                    <div className="mr-4 mt-1">
+                      {SourceIcons[notification.source] || <Bell className="h-8 w-8" />}
+                    </div>
+                    <div className="flex-1">
+                      <div className="flex items-start justify-between">
+                        <div>
+                          <h3 className="font-medium">
+                            {notification.title}
+                            {!notification.isRead && (
+                              <Badge className="ml-2 bg-blue-500">New</Badge>
+                            )}
+                          </h3>
+                          <p className="text-sm text-muted-foreground capitalize">
+                            From {notification.source} • {formatDistanceToNow(new Date(notification.timestamp), { addSuffix: true })}
+                          </p>
+                        </div>
+                        <div className="flex space-x-2 ml-4">
+                          {!notification.isRead && (
+                            <Button
+                              size="sm"
+                              variant="ghost"
+                              onClick={() => handleMarkAsRead(notification)}
+                              title="Mark as read"
+                            >
+                              <Check className="h-4 w-4" />
+                            </Button>
+                          )}
+                          {notification.link && (
+                            <Link href={notification.link} target="_blank">
+                              <Button
+                                size="sm"
+                                variant="ghost"
+                                title="Open link"
+                              >
+                                <ExternalLink className="h-4 w-4" />
+                              </Button>
+                            </Link>
+                          )}
+                        </div>
+                      </div>
+                      <p className="mt-2">{notification.message}</p>
+                    </div>
+                  </div>
+                </CardContent>
+              </Card>
+            ))
+          )}
+        </TabsContent>
+      </Tabs>
     </div>
-  )
+  );
 }
 
diff --git a/components/main-nav.tsx b/components/main-nav.tsx
index 3a9b08de..e5ddc13e 100644
--- a/components/main-nav.tsx
+++ b/components/main-nav.tsx
@@ -36,6 +36,7 @@ import {
 } from "@/components/ui/dropdown-menu";
 import { format } from 'date-fns';
 import { fr } from 'date-fns/locale';
+import { NotificationBadge } from './notification-badge';
 
 const requestNotificationPermission = async () => {
   try {
@@ -280,12 +281,7 @@ export function MainNav() {
               <span>{formattedTime}</span>
             </div>
 
-            <Link
-              href='/notifications'
-              className='text-white/80 hover:text-white'
-            >
-              <Bell className='w-5 h-5' />
-            </Link>
+            <NotificationBadge />
 
             {status === "authenticated" && session?.user ? (
               <DropdownMenu>
diff --git a/components/notification-badge.tsx b/components/notification-badge.tsx
new file mode 100644
index 00000000..cdffe3f0
--- /dev/null
+++ b/components/notification-badge.tsx
@@ -0,0 +1,35 @@
+import React from 'react';
+import Link from 'next/link';
+import { Bell } from 'lucide-react';
+import { Badge } from '@/components/ui/badge';
+import { useNotifications } from '@/hooks/use-notifications';
+
+interface NotificationBadgeProps {
+  className?: string;
+}
+
+export function NotificationBadge({ className }: NotificationBadgeProps) {
+  const { notificationCount } = useNotifications();
+  const hasUnread = notificationCount.unread > 0;
+  
+  return (
+    <div className={`relative ${className || ''}`}>
+      <Link
+        href='/notifications'
+        className='text-white/80 hover:text-white transition-colors relative'
+        aria-label={`Notifications${hasUnread ? ` (${notificationCount.unread} unread)` : ''}`}
+      >
+        <Bell className='w-5 h-5' />
+        {hasUnread && (
+          <Badge 
+            variant="notification" 
+            size="notification"
+            className="absolute -top-2 -right-2"
+          >
+            {notificationCount.unread > 99 ? '99+' : notificationCount.unread}
+          </Badge>
+        )}
+      </Link>
+    </div>
+  );
+} 
\ No newline at end of file
diff --git a/components/ui/badge.tsx b/components/ui/badge.tsx
index f000e3ef..7920f63b 100644
--- a/components/ui/badge.tsx
+++ b/components/ui/badge.tsx
@@ -15,10 +15,25 @@ const badgeVariants = cva(
         destructive:
           "border-transparent bg-destructive text-destructive-foreground hover:bg-destructive/80",
         outline: "text-foreground",
+        notification:
+          "border-transparent bg-red-500 text-white hover:bg-red-600 absolute -top-1 -right-1 px-1.5 py-0.5 min-w-[1.25rem] h-5 flex items-center justify-center",
       },
+      shape: {
+        default: "rounded-full",
+        pill: "rounded-full",
+        square: "rounded-md"
+      },
+      size: {
+        default: "text-xs px-2.5 py-0.5",
+        sm: "text-xs px-2 py-0.25 h-3.5 min-w-[1rem]",
+        lg: "text-sm px-3 py-1",
+        notification: "text-xs px-1.5 py-0.5 h-5 min-w-[1.25rem]"
+      }
     },
     defaultVariants: {
       variant: "default",
+      shape: "default",
+      size: "default"
     },
   }
 )
@@ -27,9 +42,18 @@ export interface BadgeProps
   extends React.HTMLAttributes<HTMLDivElement>,
     VariantProps<typeof badgeVariants> {}
 
-function Badge({ className, variant, ...props }: BadgeProps) {
+function Badge({
+  className,
+  variant,
+  shape,
+  size,
+  ...props
+}: BadgeProps) {
   return (
-    <div className={cn(badgeVariants({ variant }), className)} {...props} />
+    <div
+      className={cn(badgeVariants({ variant, shape, size }), className)}
+      {...props}
+    />
   )
 }
 
diff --git a/hooks/use-notifications.ts b/hooks/use-notifications.ts
new file mode 100644
index 00000000..e5e60b9e
--- /dev/null
+++ b/hooks/use-notifications.ts
@@ -0,0 +1,194 @@
+import { useState, useEffect, useCallback } from 'react';
+import { useSession } from 'next-auth/react';
+import { Notification, NotificationCount } from '@/lib/types/notification';
+
+// Default empty notification count
+const defaultNotificationCount: NotificationCount = {
+  total: 0,
+  unread: 0,
+  sources: {}
+};
+
+export function useNotifications() {
+  const { data: session, status } = useSession();
+  const [notifications, setNotifications] = useState<Notification[]>([]);
+  const [notificationCount, setNotificationCount] = useState<NotificationCount>(defaultNotificationCount);
+  const [loading, setLoading] = useState(false);
+  const [error, setError] = useState<string | null>(null);
+  const [pollingInterval, setPollingInterval] = useState<NodeJS.Timeout | null>(null);
+
+  // Fetch notification count
+  const fetchNotificationCount = useCallback(async () => {
+    if (!session?.user) return;
+    
+    try {
+      setError(null);
+      
+      const response = await fetch('/api/notifications/count');
+      
+      if (!response.ok) {
+        const errorData = await response.json();
+        console.error('Failed to fetch notification count:', errorData);
+        setError(errorData.error || 'Failed to fetch notification count');
+        return;
+      }
+      
+      const data = await response.json();
+      setNotificationCount(data);
+    } catch (err) {
+      console.error('Error fetching notification count:', err);
+      setError('Failed to fetch notification count');
+    }
+  }, [session?.user]);
+
+  // Fetch notifications
+  const fetchNotifications = useCallback(async (page = 1, limit = 20) => {
+    if (!session?.user) return;
+    
+    setLoading(true);
+    setError(null);
+    
+    try {
+      const response = await fetch(`/api/notifications?page=${page}&limit=${limit}`);
+      
+      if (!response.ok) {
+        const errorData = await response.json();
+        console.error('Failed to fetch notifications:', errorData);
+        setError(errorData.error || 'Failed to fetch notifications');
+        return;
+      }
+      
+      const data = await response.json();
+      setNotifications(data.notifications);
+    } catch (err) {
+      console.error('Error fetching notifications:', err);
+      setError('Failed to fetch notifications');
+    } finally {
+      setLoading(false);
+    }
+  }, [session?.user]);
+
+  // Mark notification as read
+  const markAsRead = useCallback(async (notificationId: string) => {
+    if (!session?.user) return;
+    
+    try {
+      const response = await fetch(`/api/notifications/${notificationId}/read`, {
+        method: 'POST',
+        headers: {
+          'Content-Type': 'application/json'
+        }
+      });
+      
+      if (!response.ok) {
+        const errorData = await response.json();
+        console.error('Failed to mark notification as read:', errorData);
+        return false;
+      }
+      
+      // Update local state
+      setNotifications(prev => 
+        prev.map(notification => 
+          notification.id === notificationId
+            ? { ...notification, isRead: true }
+            : notification
+        )
+      );
+      
+      // Refresh notification count
+      fetchNotificationCount();
+      
+      return true;
+    } catch (err) {
+      console.error('Error marking notification as read:', err);
+      return false;
+    }
+  }, [session?.user, fetchNotificationCount]);
+
+  // Mark all notifications as read
+  const markAllAsRead = useCallback(async () => {
+    if (!session?.user) return;
+    
+    try {
+      const response = await fetch('/api/notifications/read-all', {
+        method: 'POST',
+        headers: {
+          'Content-Type': 'application/json'
+        }
+      });
+      
+      if (!response.ok) {
+        const errorData = await response.json();
+        console.error('Failed to mark all notifications as read:', errorData);
+        return false;
+      }
+      
+      // Update local state
+      setNotifications(prev => 
+        prev.map(notification => ({ ...notification, isRead: true }))
+      );
+      
+      // Refresh notification count
+      fetchNotificationCount();
+      
+      return true;
+    } catch (err) {
+      console.error('Error marking all notifications as read:', err);
+      return false;
+    }
+  }, [session?.user, fetchNotificationCount]);
+
+  // Start polling for notification count
+  const startPolling = useCallback((interval = 30000) => {
+    if (pollingInterval) {
+      clearInterval(pollingInterval);
+    }
+    
+    const id = setInterval(() => {
+      fetchNotificationCount();
+    }, interval);
+    
+    setPollingInterval(id);
+    
+    return () => {
+      clearInterval(id);
+      setPollingInterval(null);
+    };
+  }, [fetchNotificationCount, pollingInterval]);
+
+  // Stop polling
+  const stopPolling = useCallback(() => {
+    if (pollingInterval) {
+      clearInterval(pollingInterval);
+      setPollingInterval(null);
+    }
+  }, [pollingInterval]);
+
+  // Initialize fetching on component mount
+  useEffect(() => {
+    if (status === 'authenticated' && session?.user) {
+      fetchNotificationCount();
+      fetchNotifications();
+      
+      // Start polling
+      const cleanup = startPolling();
+      
+      return () => {
+        cleanup();
+      };
+    }
+  }, [status, session?.user, fetchNotificationCount, fetchNotifications, startPolling]);
+
+  return {
+    notifications,
+    notificationCount,
+    loading,
+    error,
+    fetchNotifications,
+    fetchNotificationCount,
+    markAsRead,
+    markAllAsRead,
+    startPolling,
+    stopPolling
+  };
+} 
\ No newline at end of file
diff --git a/lib/services/notifications/leantime-adapter.ts b/lib/services/notifications/leantime-adapter.ts
new file mode 100644
index 00000000..676342a9
--- /dev/null
+++ b/lib/services/notifications/leantime-adapter.ts
@@ -0,0 +1,236 @@
+import { Notification, NotificationCount } from '@/lib/types/notification';
+import { NotificationAdapter } from './notification-adapter.interface';
+import { prisma } from '@/lib/prisma';
+
+// Leantime notification type from their API
+interface LeantimeNotification {
+  id: number;
+  userId: number;
+  username: string;
+  message: string;
+  type: string;
+  moduleId: number;
+  url: string;
+  read: number; // 0 for unread, 1 for read
+  date: string; // ISO format date
+}
+
+export class LeantimeAdapter implements NotificationAdapter {
+  readonly sourceName = 'leantime';
+  private apiUrl: string;
+  private apiKey: string;
+
+  constructor() {
+    // Load from environment or database config
+    this.apiUrl = process.env.LEANTIME_API_URL || '';
+    this.apiKey = process.env.LEANTIME_API_KEY || '';
+  }
+
+  private async getLeantimeCredentials(userId: string): Promise<{ url: string, apiKey: string } | null> {
+    // Get Leantime credentials from the database for this user
+    const credentials = await prisma.userServiceCredentials.findFirst({
+      where: {
+        userId: userId,
+        service: 'leantime'
+      }
+    });
+
+    if (!credentials) {
+      return null;
+    }
+
+    return {
+      url: credentials.serviceUrl || this.apiUrl,
+      apiKey: credentials.accessToken || this.apiKey,
+    };
+  }
+
+  async getNotifications(userId: string, page = 1, limit = 20): Promise<Notification[]> {
+    const credentials = await this.getLeantimeCredentials(userId);
+    if (!credentials) {
+      return [];
+    }
+
+    try {
+      // Calculate offset for pagination
+      const offset = (page - 1) * limit;
+      
+      // Make request to Leantime API
+      const response = await fetch(
+        `${credentials.url}/api/notifications?limit=${limit}&offset=${offset}`,
+        {
+          headers: {
+            'Authorization': `Bearer ${credentials.apiKey}`,
+            'Content-Type': 'application/json'
+          }
+        }
+      );
+
+      if (!response.ok) {
+        console.error(`Failed to fetch Leantime notifications: ${response.status}`);
+        return [];
+      }
+
+      const data = await response.json();
+      return this.transformNotifications(data, userId);
+    } catch (error) {
+      console.error('Error fetching Leantime notifications:', error);
+      return [];
+    }
+  }
+
+  async getNotificationCount(userId: string): Promise<NotificationCount> {
+    const credentials = await this.getLeantimeCredentials(userId);
+    if (!credentials) {
+      return {
+        total: 0,
+        unread: 0,
+        sources: {
+          leantime: {
+            total: 0,
+            unread: 0
+          }
+        }
+      };
+    }
+
+    try {
+      // Make request to Leantime API
+      const response = await fetch(
+        `${credentials.url}/api/notifications/count`,
+        {
+          headers: {
+            'Authorization': `Bearer ${credentials.apiKey}`,
+            'Content-Type': 'application/json'
+          }
+        }
+      );
+
+      if (!response.ok) {
+        console.error(`Failed to fetch Leantime notification count: ${response.status}`);
+        return {
+          total: 0,
+          unread: 0,
+          sources: {
+            leantime: {
+              total: 0,
+              unread: 0
+            }
+          }
+        };
+      }
+
+      const data = await response.json();
+      const unreadCount = data.unread || 0;
+      const totalCount = data.total || 0;
+
+      return {
+        total: totalCount,
+        unread: unreadCount,
+        sources: {
+          leantime: {
+            total: totalCount,
+            unread: unreadCount
+          }
+        }
+      };
+    } catch (error) {
+      console.error('Error fetching Leantime notification count:', error);
+      return {
+        total: 0,
+        unread: 0,
+        sources: {
+          leantime: {
+            total: 0,
+            unread: 0
+          }
+        }
+      };
+    }
+  }
+
+  async markAsRead(userId: string, notificationId: string): Promise<boolean> {
+    const credentials = await this.getLeantimeCredentials(userId);
+    if (!credentials) {
+      return false;
+    }
+
+    try {
+      // Extract the source ID from our compound ID
+      const sourceId = notificationId.replace(`${this.sourceName}-`, '');
+      
+      // Make request to Leantime API
+      const response = await fetch(
+        `${credentials.url}/api/notifications/${sourceId}/read`,
+        {
+          method: 'POST',
+          headers: {
+            'Authorization': `Bearer ${credentials.apiKey}`,
+            'Content-Type': 'application/json'
+          }
+        }
+      );
+
+      return response.ok;
+    } catch (error) {
+      console.error('Error marking Leantime notification as read:', error);
+      return false;
+    }
+  }
+
+  async markAllAsRead(userId: string): Promise<boolean> {
+    const credentials = await this.getLeantimeCredentials(userId);
+    if (!credentials) {
+      return false;
+    }
+
+    try {
+      // Make request to Leantime API
+      const response = await fetch(
+        `${credentials.url}/api/notifications/read-all`,
+        {
+          method: 'POST',
+          headers: {
+            'Authorization': `Bearer ${credentials.apiKey}`,
+            'Content-Type': 'application/json'
+          }
+        }
+      );
+
+      return response.ok;
+    } catch (error) {
+      console.error('Error marking all Leantime notifications as read:', error);
+      return false;
+    }
+  }
+
+  async isConfigured(): Promise<boolean> {
+    return !!(this.apiUrl && this.apiKey);
+  }
+
+  private transformNotifications(data: LeantimeNotification[], userId: string): Notification[] {
+    if (!Array.isArray(data)) {
+      return [];
+    }
+
+    return data.map(notification => ({
+      id: `${this.sourceName}-${notification.id}`,
+      source: this.sourceName as 'leantime',
+      sourceId: notification.id.toString(),
+      type: notification.type,
+      title: notification.type, // Leantime doesn't provide a separate title
+      message: notification.message,
+      link: notification.url,
+      isRead: notification.read === 1,
+      timestamp: new Date(notification.date),
+      priority: 'normal', // Default priority as Leantime doesn't specify
+      user: {
+        id: userId,
+        name: notification.username
+      },
+      metadata: {
+        moduleId: notification.moduleId
+      }
+    }));
+  }
+} 
\ No newline at end of file
diff --git a/lib/services/notifications/notification-adapter.interface.ts b/lib/services/notifications/notification-adapter.interface.ts
new file mode 100644
index 00000000..18fb9406
--- /dev/null
+++ b/lib/services/notifications/notification-adapter.interface.ts
@@ -0,0 +1,45 @@
+import { Notification, NotificationCount } from '@/lib/types/notification';
+
+export interface NotificationAdapter {
+  /**
+   * The source name of this notification adapter
+   */
+  readonly sourceName: string;
+  
+  /**
+   * Fetch all notifications for a user
+   * @param userId The user ID
+   * @param page Page number for pagination
+   * @param limit Number of items per page
+   * @returns Promise with notification data
+   */
+  getNotifications(userId: string, page?: number, limit?: number): Promise<Notification[]>;
+  
+  /**
+   * Get count of notifications for a user
+   * @param userId The user ID
+   * @returns Promise with notification count data
+   */
+  getNotificationCount(userId: string): Promise<NotificationCount>;
+  
+  /**
+   * Mark a specific notification as read
+   * @param userId The user ID
+   * @param notificationId The notification ID
+   * @returns Promise with success status
+   */
+  markAsRead(userId: string, notificationId: string): Promise<boolean>;
+  
+  /**
+   * Mark all notifications as read
+   * @param userId The user ID
+   * @returns Promise with success status
+   */
+  markAllAsRead(userId: string): Promise<boolean>;
+  
+  /**
+   * Check if this adapter is configured and ready to use
+   * @returns Promise with boolean indicating if adapter is ready
+   */
+  isConfigured(): Promise<boolean>;
+} 
\ No newline at end of file
diff --git a/lib/services/notifications/notification-service.ts b/lib/services/notifications/notification-service.ts
new file mode 100644
index 00000000..9d1f6225
--- /dev/null
+++ b/lib/services/notifications/notification-service.ts
@@ -0,0 +1,296 @@
+import { Notification, NotificationCount } from '@/lib/types/notification';
+import { NotificationAdapter } from './notification-adapter.interface';
+import { LeantimeAdapter } from './leantime-adapter';
+import { getRedisClient } from '@/lib/redis';
+
+export class NotificationService {
+  private adapters: Map<string, NotificationAdapter> = new Map();
+  private static instance: NotificationService;
+  
+  // Cache keys and TTLs
+  private static NOTIFICATION_COUNT_CACHE_KEY = (userId: string) => `notifications:count:${userId}`;
+  private static NOTIFICATIONS_LIST_CACHE_KEY = (userId: string, page: number, limit: number) => 
+    `notifications:list:${userId}:${page}:${limit}`;
+  private static COUNT_CACHE_TTL = 30; // 30 seconds
+  private static LIST_CACHE_TTL = 300; // 5 minutes
+  private static REFRESH_LOCK_KEY = (userId: string) => `notifications:refresh:lock:${userId}`;
+  private static REFRESH_LOCK_TTL = 30; // 30 seconds
+
+  constructor() {
+    // Register adapters
+    this.registerAdapter(new LeantimeAdapter());
+    
+    // More adapters will be added as they are implemented
+    // this.registerAdapter(new NextcloudAdapter());
+    // this.registerAdapter(new GiteaAdapter());
+    // this.registerAdapter(new DolibarrAdapter());
+    // this.registerAdapter(new MoodleAdapter());
+  }
+
+  /**
+   * Get the singleton instance of the notification service
+   */
+  public static getInstance(): NotificationService {
+    if (!NotificationService.instance) {
+      NotificationService.instance = new NotificationService();
+    }
+    return NotificationService.instance;
+  }
+
+  /**
+   * Register a notification adapter
+   */
+  private registerAdapter(adapter: NotificationAdapter): void {
+    this.adapters.set(adapter.sourceName, adapter);
+    console.log(`Registered notification adapter: ${adapter.sourceName}`);
+  }
+
+  /**
+   * Get all notifications for a user from all configured sources
+   */
+  async getNotifications(userId: string, page = 1, limit = 20): Promise<Notification[]> {
+    const redis = getRedisClient();
+    const cacheKey = NotificationService.NOTIFICATIONS_LIST_CACHE_KEY(userId, page, limit);
+
+    // Try to get from cache first
+    try {
+      const cachedData = await redis.get(cacheKey);
+      if (cachedData) {
+        console.log(`[NOTIFICATION_SERVICE] Using cached notifications for user ${userId}`);
+        
+        // Schedule background refresh if TTL is less than half the original value
+        const ttl = await redis.ttl(cacheKey);
+        if (ttl < NotificationService.LIST_CACHE_TTL / 2) {
+          this.scheduleBackgroundRefresh(userId);
+        }
+        
+        return JSON.parse(cachedData);
+      }
+    } catch (error) {
+      console.error('Error retrieving notifications from cache:', error);
+    }
+
+    // No cached data, fetch from all adapters
+    console.log(`[NOTIFICATION_SERVICE] Fetching notifications for user ${userId}`);
+    
+    const allNotifications: Notification[] = [];
+    const promises = Array.from(this.adapters.values())
+      .map(adapter => adapter.isConfigured()
+        .then(configured => configured ? adapter.getNotifications(userId, page, limit) : [])
+        .catch(error => {
+          console.error(`Error fetching notifications from ${adapter.sourceName}:`, error);
+          return [];
+        })
+      );
+      
+    const results = await Promise.all(promises);
+    
+    // Combine all notifications
+    results.forEach(notifications => {
+      allNotifications.push(...notifications);
+    });
+    
+    // Sort by timestamp (newest first)
+    allNotifications.sort((a, b) => b.timestamp.getTime() - a.timestamp.getTime());
+    
+    // Store in cache
+    try {
+      await redis.set(
+        cacheKey,
+        JSON.stringify(allNotifications),
+        'EX',
+        NotificationService.LIST_CACHE_TTL
+      );
+    } catch (error) {
+      console.error('Error caching notifications:', error);
+    }
+    
+    return allNotifications;
+  }
+
+  /**
+   * Get notification counts for a user
+   */
+  async getNotificationCount(userId: string): Promise<NotificationCount> {
+    const redis = getRedisClient();
+    const cacheKey = NotificationService.NOTIFICATION_COUNT_CACHE_KEY(userId);
+    
+    // Try to get from cache first
+    try {
+      const cachedData = await redis.get(cacheKey);
+      if (cachedData) {
+        console.log(`[NOTIFICATION_SERVICE] Using cached notification counts for user ${userId}`);
+        
+        // Schedule background refresh if TTL is less than half the original value
+        const ttl = await redis.ttl(cacheKey);
+        if (ttl < NotificationService.COUNT_CACHE_TTL / 2) {
+          this.scheduleBackgroundRefresh(userId);
+        }
+        
+        return JSON.parse(cachedData);
+      }
+    } catch (error) {
+      console.error('Error retrieving notification counts from cache:', error);
+    }
+    
+    // No cached data, fetch counts from all adapters
+    console.log(`[NOTIFICATION_SERVICE] Fetching notification counts for user ${userId}`);
+    
+    const aggregatedCount: NotificationCount = {
+      total: 0,
+      unread: 0,
+      sources: {}
+    };
+    
+    const promises = Array.from(this.adapters.values())
+      .map(adapter => adapter.isConfigured()
+        .then(configured => configured ? adapter.getNotificationCount(userId) : null)
+        .catch(error => {
+          console.error(`Error fetching notification count from ${adapter.sourceName}:`, error);
+          return null;
+        })
+      );
+      
+    const results = await Promise.all(promises);
+    
+    // Combine all counts
+    results.forEach(count => {
+      if (!count) return;
+      
+      aggregatedCount.total += count.total;
+      aggregatedCount.unread += count.unread;
+      
+      // Merge source-specific counts
+      Object.entries(count.sources).forEach(([source, sourceCount]) => {
+        aggregatedCount.sources[source] = sourceCount;
+      });
+    });
+    
+    // Store in cache
+    try {
+      await redis.set(
+        cacheKey,
+        JSON.stringify(aggregatedCount),
+        'EX',
+        NotificationService.COUNT_CACHE_TTL
+      );
+    } catch (error) {
+      console.error('Error caching notification counts:', error);
+    }
+    
+    return aggregatedCount;
+  }
+
+  /**
+   * Mark a notification as read
+   */
+  async markAsRead(userId: string, notificationId: string): Promise<boolean> {
+    // Extract the source from the notification ID (format: "source-id")
+    const [source, ...idParts] = notificationId.split('-');
+    const sourceId = idParts.join('-'); // Reconstruct the ID in case it has hyphens
+    
+    if (!source || !this.adapters.has(source)) {
+      return false;
+    }
+    
+    const adapter = this.adapters.get(source)!;
+    const success = await adapter.markAsRead(userId, notificationId);
+    
+    if (success) {
+      // Invalidate caches
+      await this.invalidateCache(userId);
+    }
+    
+    return success;
+  }
+
+  /**
+   * Mark all notifications from all sources as read
+   */
+  async markAllAsRead(userId: string): Promise<boolean> {
+    const promises = Array.from(this.adapters.values())
+      .map(adapter => adapter.isConfigured()
+        .then(configured => configured ? adapter.markAllAsRead(userId) : true)
+        .catch(error => {
+          console.error(`Error marking all notifications as read for ${adapter.sourceName}:`, error);
+          return false;
+        })
+      );
+      
+    const results = await Promise.all(promises);
+    const success = results.every(result => result);
+    
+    if (success) {
+      // Invalidate caches
+      await this.invalidateCache(userId);
+    }
+    
+    return success;
+  }
+
+  /**
+   * Invalidate notification caches for a user
+   */
+  private async invalidateCache(userId: string): Promise<void> {
+    try {
+      const redis = getRedisClient();
+      
+      // Get all cache keys for this user
+      const countKey = NotificationService.NOTIFICATION_COUNT_CACHE_KEY(userId);
+      const listKeysPattern = `notifications:list:${userId}:*`;
+      
+      // Delete count cache
+      await redis.del(countKey);
+      
+      // Find and delete list caches
+      const listKeys = await redis.keys(listKeysPattern);
+      if (listKeys.length > 0) {
+        await redis.del(...listKeys);
+      }
+      
+      console.log(`[NOTIFICATION_SERVICE] Invalidated notification caches for user ${userId}`);
+    } catch (error) {
+      console.error('Error invalidating notification caches:', error);
+    }
+  }
+
+  /**
+   * Schedule a background refresh of notification data
+   */
+  private async scheduleBackgroundRefresh(userId: string): Promise<void> {
+    const redis = getRedisClient();
+    const lockKey = NotificationService.REFRESH_LOCK_KEY(userId);
+    
+    // Try to acquire a lock to prevent multiple refreshes
+    const lockAcquired = await redis.set(
+      lockKey,
+      Date.now().toString(),
+      'EX',
+      NotificationService.REFRESH_LOCK_TTL,
+      'NX' // Set only if the key doesn't exist
+    );
+    
+    if (!lockAcquired) {
+      // Another process is already refreshing
+      return;
+    }
+    
+    // Use setTimeout to make this non-blocking
+    setTimeout(async () => {
+      try {
+        console.log(`[NOTIFICATION_SERVICE] Background refresh started for user ${userId}`);
+        
+        // Refresh counts and notifications (for first page)
+        await this.getNotificationCount(userId);
+        await this.getNotifications(userId, 1, 20);
+        
+        console.log(`[NOTIFICATION_SERVICE] Background refresh completed for user ${userId}`);
+      } catch (error) {
+        console.error(`[NOTIFICATION_SERVICE] Background refresh failed for user ${userId}:`, error);
+      } finally {
+        // Release the lock
+        await redis.del(lockKey).catch(() => {});
+      }
+    }, 0);
+  }
+} 
\ No newline at end of file
diff --git a/lib/types/notification.ts b/lib/types/notification.ts
new file mode 100644
index 00000000..a93a3cdc
--- /dev/null
+++ b/lib/types/notification.ts
@@ -0,0 +1,28 @@
+export interface Notification {
+  id: string;
+  source: 'leantime' | 'nextcloud' | 'gitea' | 'dolibarr' | 'moodle';
+  sourceId: string; // Original ID from the source system
+  type: string; // Type of notification (e.g., 'task', 'mention', 'comment')
+  title: string;
+  message: string;
+  link?: string; // Link to view the item in the source system
+  isRead: boolean;
+  timestamp: Date;
+  priority: 'low' | 'normal' | 'high';
+  user: {
+    id: string;
+    name?: string;
+  };
+  metadata?: Record<string, any>; // Additional source-specific data
+}
+
+export interface NotificationCount {
+  total: number;
+  unread: number;
+  sources: {
+    [key: string]: {
+      total: number;
+      unread: number;
+    }
+  };
+} 
\ No newline at end of file