diff --git a/src/routes/tools/stopwatch-timer/+page.svelte b/src/routes/tools/stopwatch-timer/+page.svelte
new file mode 100644
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+++ b/src/routes/tools/stopwatch-timer/+page.svelte
@@ -0,0 +1,421 @@
+<script lang="ts">
+	import { Button } from '$lib/components/ui/button';
+	import { Card, CardContent, CardHeader, CardTitle } from '$lib/components/ui/card';
+	import { Tabs, TabsContent, TabsList, TabsTrigger } from '$lib/components/ui/tabs';
+	import { Input } from '$lib/components/ui/input';
+	import { Label } from '$lib/components/ui/label';
+	import { Badge } from '$lib/components/ui/badge';
+	import { Separator } from '$lib/components/ui/separator';
+	import { AlertCircle, Play, Pause, Square, RotateCcw, Timer, Clock } from '@lucide/svelte';
+	import { onMount, onDestroy } from 'svelte';
+
+	// Stopwatch state
+	let stopwatchTime = $state(0); // in milliseconds
+	let stopwatchRunning = $state(false);
+	let stopwatchLaps = $state<number[]>([]);
+	let stopwatchInterval: NodeJS.Timeout | null = null;
+
+	// Timer state
+	let timerMinutes = $state(5);
+	let timerSeconds = $state(0);
+	let timerTotalTime = $state(0); // in milliseconds
+	let timerCurrentTime = $state(0); // in milliseconds
+	let timerRunning = $state(false);
+	let timerInterval: NodeJS.Timeout | null = null;
+	let timerFinished = $state(false);
+
+	// Format time from milliseconds to MM:SS.mmm
+	function formatTime(ms: number, showMilliseconds = true): string {
+		const minutes = Math.floor(ms / 60000);
+		const seconds = Math.floor((ms % 60000) / 1000);
+		const milliseconds = Math.floor((ms % 1000) / 10);
+
+		if (showMilliseconds) {
+			return `${minutes.toString().padStart(2, '0')}:${seconds.toString().padStart(2, '0')}.${milliseconds.toString().padStart(2, '0')}`;
+		} else {
+			return `${minutes.toString().padStart(2, '0')}:${seconds.toString().padStart(2, '0')}`;
+		}
+	}
+
+	// Stopwatch functions
+	function startStopwatch() {
+		if (!stopwatchRunning) {
+			stopwatchRunning = true;
+			const startTime = Date.now() - stopwatchTime;
+			stopwatchInterval = setInterval(() => {
+				stopwatchTime = Date.now() - startTime;
+			}, 10);
+		}
+	}
+
+	function pauseStopwatch() {
+		stopwatchRunning = false;
+		if (stopwatchInterval) {
+			clearInterval(stopwatchInterval);
+			stopwatchInterval = null;
+		}
+	}
+
+	function resetStopwatch() {
+		pauseStopwatch();
+		stopwatchTime = 0;
+		stopwatchLaps = [];
+	}
+
+	function lapStopwatch() {
+		if (stopwatchRunning) {
+			stopwatchLaps = [...stopwatchLaps, stopwatchTime];
+		}
+	}
+
+	function removeLap(index: number) {
+		stopwatchLaps = stopwatchLaps.filter((_, i) => i !== index);
+	}
+
+	// Timer functions
+	function startTimer() {
+		if (timerCurrentTime <= 0) {
+			timerTotalTime = (timerMinutes * 60 + timerSeconds) * 1000;
+			timerCurrentTime = timerTotalTime;
+		}
+
+		if (timerCurrentTime > 0 && !timerRunning) {
+			timerRunning = true;
+			timerFinished = false;
+			const startTime = Date.now();
+			const initialTime = timerCurrentTime;
+
+			timerInterval = setInterval(() => {
+				const elapsed = Date.now() - startTime;
+				timerCurrentTime = Math.max(0, initialTime - elapsed);
+
+				if (timerCurrentTime <= 0) {
+					timerRunning = false;
+					timerFinished = true;
+					if (timerInterval) {
+						clearInterval(timerInterval);
+						timerInterval = null;
+					}
+					// Play notification sound or show notification
+					playNotification();
+				}
+			}, 10);
+		}
+	}
+
+	function pauseTimer() {
+		timerRunning = false;
+		if (timerInterval) {
+			clearInterval(timerInterval);
+			timerInterval = null;
+		}
+	}
+
+	function resetTimer() {
+		pauseTimer();
+		timerCurrentTime = 0;
+		timerFinished = false;
+	}
+
+	function playNotification() {
+		// Create a simple beep sound
+		try {
+			const audioContext = new (window.AudioContext || (window as any).webkitAudioContext)();
+			const oscillator = audioContext.createOscillator();
+			const gainNode = audioContext.createGain();
+
+			oscillator.connect(gainNode);
+			gainNode.connect(audioContext.destination);
+
+			oscillator.frequency.value = 800;
+			oscillator.type = 'sine';
+
+			gainNode.gain.setValueAtTime(0.3, audioContext.currentTime);
+			gainNode.gain.exponentialRampToValueAtTime(0.01, audioContext.currentTime + 1);
+
+			oscillator.start(audioContext.currentTime);
+			oscillator.stop(audioContext.currentTime + 1);
+		} catch (error) {
+			console.warn('Could not play notification sound:', error);
+		}
+	}
+
+	// Calculate timer progress percentage
+	$effect(() => {
+		if (timerTotalTime > 0) {
+			const progress = ((timerTotalTime - timerCurrentTime) / timerTotalTime) * 100;
+			// You could use this for a progress bar if needed
+		}
+	});
+
+	// Cleanup intervals on component destroy
+	onDestroy(() => {
+		if (stopwatchInterval) clearInterval(stopwatchInterval);
+		if (timerInterval) clearInterval(timerInterval);
+	});
+</script>
+
+<div class="container mx-auto flex h-screen max-w-4xl items-center justify-center p-4">
+	<Tabs value="stopwatch" class="w-full">
+		<TabsList class="mb-6 grid w-full grid-cols-2">
+			<TabsTrigger value="stopwatch" class="flex items-center gap-2">
+				<Clock class="h-4 w-4" />
+				Stopwatch
+			</TabsTrigger>
+			<TabsTrigger value="timer" class="flex items-center gap-2">
+				<Timer class="h-4 w-4" />
+				Timer
+			</TabsTrigger>
+		</TabsList>
+
+		<!-- Stopwatch Tab -->
+		<TabsContent value="stopwatch" class="space-y-6">
+			<Card>
+				<CardHeader>
+					<CardTitle class="flex items-center gap-2">
+						<Clock class="h-5 w-5" />
+						Stopwatch
+					</CardTitle>
+				</CardHeader>
+				<CardContent class="space-y-6">
+					<!-- Time Display -->
+					<div class="text-center">
+						<div class="mb-4 font-mono text-6xl font-bold tabular-nums">
+							{formatTime(stopwatchTime)}
+						</div>
+						{#if stopwatchRunning}
+							<Badge variant="default" class="text-sm">
+								<div class="mr-2 h-2 w-2 animate-pulse rounded-full bg-green-500"></div>
+								Running
+							</Badge>
+						{:else}
+							<Badge variant="secondary" class="text-sm">Stopped</Badge>
+						{/if}
+					</div>
+
+					<!-- Controls -->
+					<div class="flex justify-center gap-4">
+						{#if !stopwatchRunning}
+							<Button onclick={startStopwatch} size="lg" class="flex items-center gap-2">
+								<Play class="h-4 w-4" />
+								Start
+							</Button>
+						{:else}
+							<Button
+								onclick={pauseStopwatch}
+								variant="secondary"
+								size="lg"
+								class="flex items-center gap-2"
+							>
+								<Pause class="h-4 w-4" />
+								Pause
+							</Button>
+						{/if}
+
+						<Button
+							onclick={resetStopwatch}
+							variant="outline"
+							size="lg"
+							class="flex items-center gap-2"
+						>
+							<RotateCcw class="h-4 w-4" />
+							Reset
+						</Button>
+
+						{#if stopwatchRunning}
+							<Button onclick={lapStopwatch} variant="outline" size="lg">Lap</Button>
+						{/if}
+					</div>
+				</CardContent>
+			</Card>
+
+			<!-- Lap Times -->
+			{#if stopwatchLaps.length > 0}
+				<Card>
+					<CardHeader>
+						<CardTitle class="text-lg">Lap Times ({stopwatchLaps.length})</CardTitle>
+					</CardHeader>
+					<CardContent>
+						<div class="max-h-60 space-y-2 overflow-y-auto">
+							{#each stopwatchLaps.toReversed() as lap, index}
+								{@const lapIndex = stopwatchLaps.length - index}
+								{@const previousLap = stopwatchLaps[stopwatchLaps.length - index - 2]}
+								{@const splitTime = previousLap ? lap - previousLap : lap}
+								<div class="bg-muted/50 flex items-center justify-between rounded-md px-3 py-2">
+									<div class="font-medium">Lap {lapIndex}</div>
+									<div class="flex items-center gap-4 font-mono">
+										<span class="text-muted-foreground text-sm">
+											+{formatTime(splitTime)}
+										</span>
+										<span class="font-semibold">{formatTime(lap)}</span>
+										<Button
+											onclick={() => removeLap(stopwatchLaps.length - index - 1)}
+											variant="ghost"
+											size="sm"
+											class="h-6 w-6 p-0"
+										>
+											×
+										</Button>
+									</div>
+								</div>
+							{/each}
+						</div>
+					</CardContent>
+				</Card>
+			{/if}
+		</TabsContent>
+
+		<!-- Timer Tab -->
+		<TabsContent value="timer" class="space-y-6">
+			<Card>
+				<CardHeader>
+					<CardTitle class="flex items-center gap-2">
+						<Timer class="h-5 w-5" />
+						Timer
+					</CardTitle>
+				</CardHeader>
+				<CardContent class="space-y-6">
+					<!-- Timer Setup -->
+					{#if !timerRunning && timerCurrentTime === 0}
+						<div class="grid grid-cols-2 gap-4">
+							<div class="space-y-2">
+								<Label for="minutes">Minutes</Label>
+								<Input
+									id="minutes"
+									type="number"
+									bind:value={timerMinutes}
+									min="0"
+									max="99"
+									class="text-center"
+								/>
+							</div>
+							<div class="space-y-2">
+								<Label for="seconds">Seconds</Label>
+								<Input
+									id="seconds"
+									type="number"
+									bind:value={timerSeconds}
+									min="0"
+									max="59"
+									class="text-center"
+								/>
+							</div>
+						</div>
+
+						<!-- Quick Timer Buttons -->
+						<div class="space-y-2">
+							<Label>Quick Set</Label>
+							<div class="flex flex-wrap gap-2">
+								{#each [{ label: '1 min', minutes: 1, seconds: 0 }, { label: '5 min', minutes: 5, seconds: 0 }, { label: '10 min', minutes: 10, seconds: 0 }, { label: '15 min', minutes: 15, seconds: 0 }, { label: '25 min', minutes: 25, seconds: 0 }, { label: '30 min', minutes: 30, seconds: 0 }, { label: '45 min', minutes: 45, seconds: 0 }, { label: '1 hour', minutes: 60, seconds: 0 }] as preset}
+									<Button
+										variant="outline"
+										size="sm"
+										onclick={() => {
+											timerMinutes = preset.minutes;
+											timerSeconds = preset.seconds;
+										}}
+									>
+										{preset.label}
+									</Button>
+								{/each}
+							</div>
+						</div>
+					{/if}
+
+					<!-- Time Display -->
+					<div class="text-center">
+						{#if timerCurrentTime > 0 || timerRunning}
+							<div
+								class="mb-4 font-mono text-6xl font-bold tabular-nums"
+								class:text-red-500={timerCurrentTime < 10000}
+							>
+								{formatTime(timerCurrentTime, false)}
+							</div>
+							{#if timerTotalTime > 0}
+								<div class="bg-muted mb-4 h-2 w-full rounded-full">
+									<div
+										class="bg-primary h-2 rounded-full transition-all duration-75"
+										style="width: {((timerTotalTime - timerCurrentTime) / timerTotalTime) * 100}%"
+									></div>
+								</div>
+							{/if}
+						{:else}
+							<div class="text-muted-foreground mb-4 font-mono text-6xl font-bold tabular-nums">
+								{String(timerMinutes).padStart(2, '0')}:{String(timerSeconds).padStart(2, '0')}
+							</div>
+						{/if}
+
+						{#if timerFinished}
+							<Badge variant="destructive" class="animate-pulse text-sm">
+								<AlertCircle class="mr-1 h-4 w-4" />
+								Time's Up!
+							</Badge>
+						{:else if timerRunning}
+							<Badge variant="default" class="text-sm">
+								<div class="mr-2 h-2 w-2 animate-pulse rounded-full bg-green-500"></div>
+								Running
+							</Badge>
+						{:else if timerCurrentTime > 0}
+							<Badge variant="secondary" class="text-sm">Paused</Badge>
+						{:else}
+							<Badge variant="outline" class="text-sm">Ready</Badge>
+						{/if}
+					</div>
+
+					<!-- Timer Controls -->
+					<div class="flex justify-center gap-4">
+						{#if !timerRunning}
+							<Button
+								onclick={startTimer}
+								size="lg"
+								class="flex items-center gap-2"
+								disabled={(timerMinutes === 0 && timerSeconds === 0) || timerFinished}
+							>
+								<Play class="h-4 w-4" />
+								Start
+							</Button>
+						{:else}
+							<Button
+								onclick={pauseTimer}
+								variant="secondary"
+								size="lg"
+								class="flex items-center gap-2"
+							>
+								<Pause class="h-4 w-4" />
+								Pause
+							</Button>
+						{/if}
+
+						<Button
+							onclick={resetTimer}
+							variant="outline"
+							size="lg"
+							class="flex items-center gap-2"
+						>
+							<Square class="h-4 w-4" />
+							Reset
+						</Button>
+					</div>
+
+					{#if timerFinished}
+						<div
+							class="rounded-lg border border-red-200 bg-red-50 p-4 text-center dark:border-red-800 dark:bg-red-950"
+						>
+							<AlertCircle class="mx-auto mb-2 h-8 w-8 text-red-500" />
+							<p class="font-medium text-red-700 dark:text-red-300">Timer completed!</p>
+							<p class="text-sm text-red-600 dark:text-red-400">
+								Your {formatTime(timerTotalTime, false)} timer has finished.
+							</p>
+						</div>
+					{/if}
+				</CardContent>
+			</Card>
+		</TabsContent>
+	</Tabs>
+</div>
+
+<style>
+	.tabular-nums {
+		font-variant-numeric: tabular-nums;
+	}
+</style>