diff --git a/apps/web/src/lib/components/AnkiImport.svelte b/apps/web/src/lib/components/AnkiImport.svelte
index db3595b..733d407 100644
--- a/apps/web/src/lib/components/AnkiImport.svelte
+++ b/apps/web/src/lib/components/AnkiImport.svelte
@@ -11,6 +11,7 @@
 <script lang="ts">
 	import { parseApkg, type ParsedAnki } from '$lib/anki/parse.ts';
 	import { importParsedAnki, type ImportResult, type ImportProgress } from '$lib/anki/import.ts';
+	import { t, tn } from '$lib/i18n/index.svelte.ts';
 
 	let fileInput = $state<HTMLInputElement | null>(null);
 	let stage = $state<'idle' | 'parsing' | 'preview' | 'importing' | 'done' | 'error'>('idle');
@@ -39,7 +40,7 @@
 			parsed = await parseApkg(file);
 			stage = 'preview';
 		} catch (e: unknown) {
-			error = e instanceof Error ? e.message : 'Datei konnte nicht gelesen werden.';
+			error = e instanceof Error ? e.message : t('import.error_label', { msg: '?' });
 			stage = 'error';
 		}
 	}
@@ -69,7 +70,7 @@
 			});
 			stage = 'done';
 		} catch (e: unknown) {
-			error = e instanceof Error ? e.message : 'Import fehlgeschlagen.';
+			error = e instanceof Error ? e.message : t('import.error_label', { msg: '?' });
 			stage = 'error';
 		}
 	}
@@ -84,7 +85,7 @@
 </script>
 
 <div class="rounded-xl border border-[var(--color-border)] bg-[var(--color-card)] p-4">
-	<div class="mb-2 text-sm font-medium">Aus Anki importieren</div>
+	<div class="mb-2 text-sm font-medium">{t('import.anki_label')}</div>
 
 	{#if stage === 'idle'}
 		<!-- svelte-ignore a11y_no_static_element_interactions -->
@@ -94,11 +95,17 @@
 			ondragover={(e) => e.preventDefault()}
 			ondrop={onDrop}
 			onclick={() => fileInput?.click()}
+			role="button"
+			tabindex="0"
+			onkeydown={(e) => {
+				if (e.key === 'Enter' || e.key === ' ') {
+					e.preventDefault();
+					fileInput?.click();
+				}
+			}}
 		>
-			<div class="mb-1">📦 .apkg-Datei hier ablegen oder klicken</div>
-			<div class="text-xs">
-				Basic, Basic + Reverse, Cloze · Bilder + Audio werden in dieser Phase nicht übernommen.
-			</div>
+			<div class="mb-1">{t('import.dropzone')}</div>
+			<div class="text-xs">{t('import.dropzone_hint')}</div>
 		</div>
 		<input
 			bind:this={fileInput}
@@ -108,36 +115,41 @@
 			onchange={onPick}
 		/>
 	{:else if stage === 'parsing'}
-		<div class="py-6 text-center text-sm text-[var(--color-muted)]">Lese {fileName}…</div>
+		<div class="py-6 text-center text-sm text-[var(--color-muted)]" aria-live="polite">
+			{t('import.parsing', { file: fileName })}
+		</div>
 	{:else if stage === 'preview' && parsed}
 		<div class="space-y-2 text-sm">
 			<div>
-				<span class="text-[var(--color-muted)]">Gefunden in</span>
+				<span class="text-[var(--color-muted)]">{t('import.preview_found')}</span>
 				<code class="rounded bg-[var(--color-border)]/40 px-1 text-xs">{fileName}</code>:
 			</div>
 			<ul class="ml-4 list-disc">
-				<li>{parsed.decks.length} {parsed.decks.length === 1 ? 'Deck' : 'Decks'}</li>
+				<li>{tn('import.preview_decks', parsed.decks.length)}</li>
 				<li>
-					{parsed.cards.length} {parsed.cards.length === 1 ? 'Karte' : 'Karten'}
+					{tn('import.preview_cards', parsed.cards.length)}
 					{#if parsed.cards.length > 0}
 						<span class="text-[var(--color-muted)]">
-							({typeBreakdown.basic} basic, {typeBreakdown.basicReverse} basic-reverse,
-							{typeBreakdown.cloze} cloze)
+							{t('import.preview_breakdown', {
+								basic: typeBreakdown.basic,
+								basic_reverse: typeBreakdown.basicReverse,
+								cloze: typeBreakdown.cloze,
+							})}
 						</span>
 					{/if}
 				</li>
 				{#if parsed.mediaByFilename.size > 0}
 					<li class="text-[var(--color-muted)]">
-						{parsed.mediaByFilename.size} Medien (werden in dieser Phase NICHT übernommen)
+						{t('import.preview_media', { n: parsed.mediaByFilename.size })}
 					</li>
 				{/if}
 				{#if parsed.skipped > 0}
-					<li>{parsed.skipped} übersprungen (unbekannter Typ)</li>
+					<li>{t('import.preview_skipped', { n: parsed.skipped })}</li>
 				{/if}
 			</ul>
 			{#if parsed.warnings.length > 0}
 				<details class="text-xs text-[var(--color-muted)]">
-					<summary class="cursor-pointer">Hinweise ({parsed.warnings.length})</summary>
+					<summary class="cursor-pointer">{t('import.preview_warnings', { n: parsed.warnings.length })}</summary>
 					<ul class="mt-1 list-disc pl-4">
 						{#each parsed.warnings.slice(0, 10) as w (w)}<li>{w}</li>{/each}
 					</ul>
@@ -148,26 +160,32 @@
 					class="rounded px-3 py-1.5 text-sm text-[var(--color-muted)] hover:text-[var(--color-fg)]"
 					onclick={reset}
 				>
-					Abbrechen
+					{t('import.cancel')}
 				</button>
 				<button
 					class="rounded bg-[var(--color-primary)] px-4 py-1.5 text-sm text-[var(--color-primary-fg)] hover:opacity-90"
 					onclick={confirmImport}
 				>
-					Importieren
+					{t('import.import_now')}
 				</button>
 			</div>
 		</div>
 	{:else if stage === 'importing'}
-		<div class="py-6 text-center text-sm text-[var(--color-muted)]">
+		<div class="py-6 text-center text-sm text-[var(--color-muted)]" aria-live="polite">
 			{#if progress.stage === 'decks'}
-				Lege Decks an · {progress.current} / {progress.total}
+				{t('import.stage_decks', { current: progress.current, total: progress.total })}
 			{:else if progress.stage === 'cards'}
-				Importiere Karten · {progress.current} / {progress.total}
+				{t('import.stage_cards', { current: progress.current, total: progress.total })}
 			{:else}
-				Fertig.
+				{t('import.stage_done')}
 			{/if}
-			<div class="mx-auto mt-3 h-1 w-48 overflow-hidden rounded-full bg-[var(--color-border)]/40">
+			<div
+				class="mx-auto mt-3 h-1 w-48 overflow-hidden rounded-full bg-[var(--color-border)]/40"
+				role="progressbar"
+				aria-valuemin="0"
+				aria-valuemax={progress.total}
+				aria-valuenow={progress.current}
+			>
 				<div
 					class="h-full bg-[var(--color-primary)] transition-all"
 					style="width: {progress.total === 0 ? 0 : (progress.current / progress.total) * 100}%"
@@ -177,12 +195,13 @@
 	{:else if stage === 'done' && result}
 		<div class="space-y-2 text-sm">
 			<div class="text-[var(--color-success,#16a34a)]">
-				✓ {result.cardsCreated} Karten in {result.decksCreated}
-				{result.decksCreated === 1 ? 'Deck' : 'Decks'} angelegt.
+				{result.decksCreated === 1
+					? t('import.done_summary_one', { cards: result.cardsCreated })
+					: t('import.done_summary', { cards: result.cardsCreated, decks: result.decksCreated })}
 			</div>
 			{#if result.failed > 0}
 				<details class="text-[var(--color-danger)]">
-					<summary class="cursor-pointer">{result.failed} Fehler</summary>
+					<summary class="cursor-pointer">{t('import.done_failures', { n: result.failed })}</summary>
 					<ul class="mt-1 list-disc pl-4 text-xs">
 						{#each result.failures.slice(0, 20) as msg (msg)}<li>{msg}</li>{/each}
 					</ul>
@@ -192,17 +211,17 @@
 				class="rounded px-3 py-1.5 text-sm text-[var(--color-muted)] hover:text-[var(--color-fg)]"
 				onclick={reset}
 			>
-				Weitere Datei
+				{t('import.done_more')}
 			</button>
 		</div>
 	{:else if stage === 'error'}
-		<div class="space-y-2 text-sm">
-			<div class="text-[var(--color-danger)]">Fehler: {error}</div>
+		<div class="space-y-2 text-sm" role="alert">
+			<div class="text-[var(--color-danger)]">{t('import.error_label', { msg: error ?? '?' })}</div>
 			<button
 				class="rounded px-3 py-1.5 text-sm text-[var(--color-muted)] hover:text-[var(--color-fg)]"
 				onclick={reset}
 			>
-				Erneut versuchen
+				{t('import.retry')}
 			</button>
 		</div>
 	{/if}
diff --git a/apps/web/src/lib/components/Header.svelte b/apps/web/src/lib/components/Header.svelte
index 17c2b02..f87b008 100644
--- a/apps/web/src/lib/components/Header.svelte
+++ b/apps/web/src/lib/components/Header.svelte
@@ -1,6 +1,7 @@
 <script lang="ts">
 	import { page } from '$app/state';
 	import { devUser } from '$lib/auth/dev-stub.svelte.ts';
+	import { i18n, t } from '$lib/i18n/index.svelte.ts';
 </script>
 
 <header
@@ -10,36 +11,60 @@
 		<a href="/" class="flex items-center gap-2 font-semibold">
 			<span
 				class="inline-flex h-7 w-7 items-center justify-center rounded bg-[var(--color-primary)] text-[var(--color-primary-fg)] text-sm"
+				aria-hidden="true"
 			>
 				C
 			</span>
-			<span>Cards</span>
+			<span>{t('app.name')}</span>
 		</a>
 
-		<nav class="flex items-center gap-6 text-sm">
+		<nav class="flex items-center gap-6 text-sm" aria-label={t('app.name')}>
 			<a
 				href="/decks"
 				class="hover:text-[var(--color-primary)]"
-				class:font-medium={page.url.pathname.startsWith('/decks')}>Decks</a
+				class:font-medium={page.url.pathname.startsWith('/decks')}>{t('nav.decks')}</a
 			>
 			<a
 				href="/study"
 				class="hover:text-[var(--color-primary)]"
-				class:font-medium={page.url.pathname.startsWith('/study')}>Lernen</a
+				class:font-medium={page.url.pathname.startsWith('/study')}>{t('nav.study')}</a
 			>
 			<a
 				href="/import"
 				class="hover:text-[var(--color-primary)]"
-				class:font-medium={page.url.pathname.startsWith('/import')}>Import</a
+				class:font-medium={page.url.pathname.startsWith('/import')}>{t('nav.import')}</a
 			>
 			<a
 				href="/stats"
 				class="hover:text-[var(--color-primary)]"
-				class:font-medium={page.url.pathname.startsWith('/stats')}>Statistik</a
+				class:font-medium={page.url.pathname.startsWith('/stats')}>{t('nav.stats')}</a
 			>
 		</nav>
 
 		<div class="flex items-center gap-3 text-sm">
+			<div
+				class="flex overflow-hidden rounded border border-[var(--color-border)] text-xs"
+				role="group"
+				aria-label="Sprache / Language"
+			>
+				<button
+					type="button"
+					class="px-2 py-1 transition-colors"
+					class:bg-primary-active={i18n.current === 'de'}
+					style:background-color={i18n.current === 'de' ? 'var(--color-primary)' : 'transparent'}
+					style:color={i18n.current === 'de' ? 'var(--color-primary-fg)' : 'var(--color-muted)'}
+					aria-pressed={i18n.current === 'de'}
+					onclick={() => i18n.set('de')}>DE</button
+				>
+				<button
+					type="button"
+					class="px-2 py-1 transition-colors"
+					style:background-color={i18n.current === 'en' ? 'var(--color-primary)' : 'transparent'}
+					style:color={i18n.current === 'en' ? 'var(--color-primary-fg)' : 'var(--color-muted)'}
+					aria-pressed={i18n.current === 'en'}
+					onclick={() => i18n.set('en')}>EN</button
+				>
+			</div>
 			{#if devUser.id}
 				<a
 					href="/account"
@@ -51,9 +76,9 @@
 			{:else}
 				<button
 					class="rounded bg-[var(--color-primary)] px-3 py-1 text-[var(--color-primary-fg)]"
-					onclick={() => devUser.set(prompt('User-ID (dev):') ?? '')}
+					onclick={() => devUser.set(prompt(t('landing.dev_user_prompt')) ?? '')}
 				>
-					Login (dev)
+					{t('nav.login_dev')}
 				</button>
 			{/if}
 		</div>
diff --git a/apps/web/src/lib/components/InboxBanner.svelte b/apps/web/src/lib/components/InboxBanner.svelte
index df5a0dc..6593568 100644
--- a/apps/web/src/lib/components/InboxBanner.svelte
+++ b/apps/web/src/lib/components/InboxBanner.svelte
@@ -1,6 +1,7 @@
 <script lang="ts">
 	import { onMount } from 'svelte';
 	import { loadInboxStats, type InboxStats } from '$lib/api/inbox.ts';
+	import { t, tn } from '$lib/i18n/index.svelte.ts';
 
 	let stats = $state<InboxStats | null>(null);
 
@@ -19,12 +20,9 @@
 		href="/decks/{stats.deck.id}"
 		class="block rounded-lg border border-[var(--color-primary)]/40 bg-[var(--color-primary)]/10 px-4 py-3 text-sm hover:bg-[var(--color-primary)]/15"
 	>
-		<span class="font-medium">📥 Inbox</span>
-		<span class="text-[var(--color-muted)]">·</span>
-		<span>
-			{stats.cardCount} eingegangene
-			{stats.cardCount === 1 ? 'Karte' : 'Karten'} aus anderen Apps
-		</span>
-		<span class="ml-1 text-[var(--color-muted)]">— sortieren →</span>
+		<span class="font-medium">{t('inbox_banner.label')}</span>
+		<span class="text-[var(--color-muted)]" aria-hidden="true">·</span>
+		<span>{tn('inbox_banner.count', stats.cardCount)}</span>
+		<span class="ml-1 text-[var(--color-muted)]">{t('inbox_banner.cta')}</span>
 	</a>
 {/if}
diff --git a/apps/web/src/lib/i18n/de.ts b/apps/web/src/lib/i18n/de.ts
new file mode 100644
index 0000000..e755850
--- /dev/null
+++ b/apps/web/src/lib/i18n/de.ts
@@ -0,0 +1,216 @@
+// Default-Locale. Schlüssel sind Punkt-getrennt nach Bereich.
+// Interpolation: {n}, {name}, {count} → simple replace.
+
+export type TranslationNode = { [key: string]: string | TranslationNode };
+
+export const de: TranslationNode = {
+	app: {
+		name: 'Cards',
+		title_suffix: 'Cards',
+	},
+	nav: {
+		decks: 'Decks',
+		study: 'Lernen',
+		import: 'Import',
+		stats: 'Statistik',
+		login_dev: 'Login (dev)',
+		account: 'Account',
+	},
+	landing: {
+		welcome: 'Lernkarten mit Spaced-Repetition.',
+		intro:
+			'Cardecky ist die föderierte Karteikarten-App des Vereins mana e.V. — FSRS-Scheduler, Cloze-Karten, Anki-Import.',
+		cta_login: 'Login (dev)',
+		dev_user_prompt: 'User-ID (dev):',
+	},
+	decks: {
+		title: 'Decks',
+		new: 'Neues Deck',
+		empty: 'Noch keine Decks.',
+		empty_cta: 'Erstes Deck anlegen',
+		loading: 'Lade…',
+		error: 'Fehler: {msg}',
+		card_count: '{n} Karten',
+		card_count_one: '1 Karte',
+		due_count: '{n} fällig',
+		delete_confirm:
+			'Deck "{name}" wirklich löschen? Alle Karten + Review-Daten gehen verloren.',
+		deleted: 'Deck "{name}" gelöscht',
+		delete_failed: 'Löschen fehlgeschlagen: {msg}',
+	},
+	deck_detail: {
+		back: '← Zurück zu Decks',
+		study_button: 'Lernen',
+		new_card: 'Neue Karte',
+		empty: 'Keine Karten in diesem Deck.',
+		empty_cta: 'Erste Karte anlegen →',
+		card_summary_due: '{cards} · {due} fällig',
+		card_delete_aria: 'Karte löschen',
+		card_delete_label: 'Löschen',
+		card_delete_confirm: 'Karte wirklich löschen? Reviews werden mit gelöscht.',
+	},
+	deck_new: {
+		title: 'Neues Deck',
+		name_label: 'Name',
+		description_label: 'Beschreibung (optional)',
+		color_label: 'Farbe (optional)',
+		create: 'Deck anlegen',
+		creating: 'Lege an…',
+		cancel: 'Abbrechen',
+		create_failed: 'Anlegen fehlgeschlagen: {msg}',
+	},
+	card_new: {
+		title: 'Neue Karte',
+		back: '← Zurück',
+		deck_label: 'Deck',
+		type_label: 'Typ',
+		type_basic: 'Basic (front → back)',
+		type_basic_reverse: 'Basic + Reverse (front ↔ back, 2 Reviews)',
+		type_cloze: 'Cloze (Lückentext, 1 Review pro Cluster)',
+		front_label: 'Vorderseite (Markdown)',
+		back_label: 'Rückseite (Markdown)',
+		back_placeholder: 'Antwort',
+		front_placeholder: '# Markdown ist erlaubt\n**fett**, _kursiv_, `code`',
+		preview_label: 'Vorschau',
+		cloze_text_label: 'Text mit Lücken (Markdown)',
+		cloze_text_placeholder: 'Die Hauptstadt von {{c1::Frankreich}} ist {{c2::Paris}}.',
+		cloze_help: '{{c1::Antwort}} definiert eine Lücke. Pro Cluster-ID (c1, c2, …) entsteht ein eigenes Review.',
+		cloze_no_clusters: 'Mindestens ein {{cN::…}}-Cluster wird gebraucht.',
+		cloze_clusters_detected: '{n} Cluster erkannt: c{ids} → {n} Reviews.',
+		cloze_preview_label: 'Vorschau (c{first} maskiert)',
+		cloze_extra_label: 'Extra (optional)',
+		cloze_extra_placeholder: 'Zusätzlicher Kontext, wird unter der Antwort gezeigt.',
+		create: 'Karte anlegen',
+		creating: 'Speichere…',
+		cancel: 'Abbrechen',
+		create_failed: 'Anlegen fehlgeschlagen: {msg}',
+		toast_basic: 'Karte angelegt',
+		toast_basic_reverse: '2 Reviews initialisiert (front→back, back→front)',
+		toast_cloze: '{n} Reviews initialisiert (1 pro Cluster)',
+		decks_load_failed: 'Decks konnten nicht geladen werden: {msg}',
+	},
+	card_edit: {
+		title: 'Karte bearbeiten',
+		back: '← Zurück zum Deck',
+		type_locked_help: 'Der Card-Type kann nicht geändert werden — die Reviews-Tabelle hängt am Type.',
+		save: 'Speichern',
+		saving: 'Speichere…',
+		cancel: 'Abbrechen',
+		delete: 'Löschen',
+		deleting: 'Lösche…',
+		delete_confirm: 'Karte wirklich löschen? Reviews werden mit gelöscht.',
+		updated: 'Karte aktualisiert',
+		save_failed: 'Speichern fehlgeschlagen: {msg}',
+		delete_failed: 'Löschen fehlgeschlagen: {msg}',
+		deleted: 'Karte gelöscht',
+	},
+	study: {
+		title: 'Lernen',
+		empty: 'Keine Decks.',
+		none_due: 'Aktuell nichts fällig.',
+		study_now: 'Jetzt lernen',
+		due_count: '{n} fällig',
+	},
+	study_session: {
+		back: '← Übersicht',
+		all_done: 'Geschafft! Alle fälligen Karten gemacht.',
+		stats: 'Reviews: {reviewed} · Wieder: {again}',
+		reveal: 'Lösung zeigen',
+		reveal_hint: 'Leertaste / Enter zum Aufdecken',
+		grade_again: 'Wieder',
+		grade_hard: 'Schwer',
+		grade_good: 'Gut',
+		grade_easy: 'Leicht',
+		grade_hint: '1=Wieder · 2=Schwer · 3=Gut · 4=Leicht',
+		loading: 'Lade…',
+		error: 'Fehler: {msg}',
+	},
+	import: {
+		title: 'Importieren',
+		intro: 'Übernimm Decks und Karten aus einer Anki-Datei (.apkg oder .colpkg). FSRS-Verlauf wird nicht übernommen — alle Karten starten als „neu".',
+		what_works_title: 'Was wird übernommen',
+		what_works_decks: 'Decks (Anki-Hierarchie Foo::Bar wird zu Foo / Bar).',
+		what_works_basic: 'Basic + Basic-Reverse: Front/Back direkt.',
+		what_works_cloze: 'Cloze: {{c1::…}} wird mit Sub-Index pro Cluster angelegt.',
+		what_skipped_title: 'Was nicht übernommen wird',
+		what_skipped_media: 'Bilder + Audio (kommen mit der Plattform-Anbindung in einer späteren Phase).',
+		what_skipped_history: 'FSRS-Lernverlauf (Anki-Reviews werden bewusst neu aufgesetzt).',
+		what_skipped_addons: 'Add-on-spezifische Card-Types (image-occlusion etc.).',
+		anki_label: 'Aus Anki importieren',
+		dropzone: '📦 .apkg-Datei hier ablegen oder klicken',
+		dropzone_hint: 'Basic, Basic + Reverse, Cloze · Bilder + Audio werden in dieser Phase nicht übernommen.',
+		parsing: 'Lese {file}…',
+		preview_found: 'Gefunden in',
+		preview_decks_one: '1 Deck',
+		preview_decks: '{n} Decks',
+		preview_cards_one: '1 Karte',
+		preview_cards: '{n} Karten',
+		preview_breakdown: '({basic} basic, {basic_reverse} basic-reverse, {cloze} cloze)',
+		preview_media: '{n} Medien (werden in dieser Phase NICHT übernommen)',
+		preview_skipped: '{n} übersprungen (unbekannter Typ)',
+		preview_warnings: 'Hinweise ({n})',
+		cancel: 'Abbrechen',
+		import_now: 'Importieren',
+		stage_decks: 'Lege Decks an · {current} / {total}',
+		stage_cards: 'Importiere Karten · {current} / {total}',
+		stage_done: 'Fertig.',
+		done_summary_one: '✓ {cards} Karten in 1 Deck angelegt.',
+		done_summary: '✓ {cards} Karten in {decks} Decks angelegt.',
+		done_failures: '{n} Fehler',
+		done_more: 'Weitere Datei',
+		error_label: 'Fehler: {msg}',
+		retry: 'Erneut versuchen',
+	},
+	inbox_banner: {
+		label: '📥 Inbox',
+		count_one: '1 eingegangene Karte aus anderen Apps',
+		count: '{n} eingegangene Karten aus anderen Apps',
+		cta: '— sortieren →',
+	},
+	account: {
+		title: 'Account',
+		user_id_label: 'User-ID',
+		logout: 'Abmelden',
+		phase2_hint:
+			'Phase-2-Hinweis: aktuell ist die Identität ein Dev-Stub (sessionStorage). Mit Auth-Föderation wechselt das auf einen mana-auth-Login gegen auth.mana.how.',
+		export_title: 'Daten-Export',
+		export_intro:
+			'Lade alle deine Cards-Daten als JSON herunter — Decks, Karten, Reviews, Study-Sessions, Tags, Media-Refs, Import-Jobs. DSGVO Art. 15/20.',
+		export_button: 'Daten exportieren',
+		export_loading: 'Lade…',
+		export_done: 'Export geladen: {decks} Decks, {cards} Karten, {reviews} Reviews.',
+		export_failed: 'Export fehlgeschlagen: {msg}',
+		delete_title: 'Konto löschen',
+		delete_intro:
+			'Löscht unwiderruflich alle deine Cards-Daten. DSGVO Art. 17. Andere mana-Apps (Memoro, Who, …) behalten ihre Daten unabhängig — wenn du dort auch löschen willst, mach das jeweils dort oder nutze die Verein-DSGVO-Sammelanfrage über mana-admin.',
+		delete_button: 'Alle Cards-Daten löschen',
+		delete_loading: 'Lösche…',
+		delete_confirm:
+			'ALLE deine Cards-Daten werden unwiderruflich gelöscht. Tippe LÖSCHEN zur Bestätigung.',
+		delete_confirm_word: 'LÖSCHEN',
+		delete_done: 'Gelöscht: {decks} Decks, {imports} Import-Jobs.',
+		delete_failed: 'Löschen fehlgeschlagen: {msg}',
+	},
+	stats: {
+		title: 'Statistik',
+		generated_at: 'Stand {date}',
+		decks: 'Decks',
+		cards: 'Karten',
+		reviews: 'Reviews',
+		due_now: 'Fällig jetzt',
+		days_title: 'Lerntage',
+		streak: 'Streak: {n} Tage · letzte 7 Tage: {total} Reviews',
+		streak_one: 'Streak: 1 Tag · letzte 7 Tage: {total} Reviews',
+		fsrs_title: 'FSRS-Status',
+		fsrs_intro: 'Verteilung deiner Karten-Reviews über die FSRS-Zustände.',
+		fsrs_new: 'Neu',
+		fsrs_learning: 'Lernend',
+		fsrs_review: 'Review',
+		fsrs_relearning: 'Relearning',
+		loading: 'Lade…',
+		error: 'Fehler: {msg}',
+	},
+	common: {
+		empty: '(leer)',
+	},
+};
diff --git a/apps/web/src/lib/i18n/en.ts b/apps/web/src/lib/i18n/en.ts
new file mode 100644
index 0000000..dc4c768
--- /dev/null
+++ b/apps/web/src/lib/i18n/en.ts
@@ -0,0 +1,213 @@
+import type { TranslationNode } from './de.ts';
+
+export const en: TranslationNode = {
+	app: {
+		name: 'Cards',
+		title_suffix: 'Cards',
+	},
+	nav: {
+		decks: 'Decks',
+		study: 'Study',
+		import: 'Import',
+		stats: 'Stats',
+		login_dev: 'Login (dev)',
+		account: 'Account',
+	},
+	landing: {
+		welcome: 'Spaced-repetition flashcards.',
+		intro:
+			'Cardecky is the federated flashcard app of mana e.V. — FSRS scheduler, cloze cards, Anki import.',
+		cta_login: 'Login (dev)',
+		dev_user_prompt: 'User ID (dev):',
+	},
+	decks: {
+		title: 'Decks',
+		new: 'New deck',
+		empty: 'No decks yet.',
+		empty_cta: 'Create first deck',
+		loading: 'Loading…',
+		error: 'Error: {msg}',
+		card_count: '{n} cards',
+		card_count_one: '1 card',
+		due_count: '{n} due',
+		delete_confirm:
+			'Really delete deck "{name}"? All cards + review data will be lost.',
+		deleted: 'Deck "{name}" deleted',
+		delete_failed: 'Delete failed: {msg}',
+	},
+	deck_detail: {
+		back: '← Back to decks',
+		study_button: 'Study',
+		new_card: 'New card',
+		empty: 'No cards in this deck.',
+		empty_cta: 'Create first card →',
+		card_summary_due: '{cards} · {due} due',
+		card_delete_aria: 'Delete card',
+		card_delete_label: 'Delete',
+		card_delete_confirm: 'Really delete card? Reviews will be deleted with it.',
+	},
+	deck_new: {
+		title: 'New deck',
+		name_label: 'Name',
+		description_label: 'Description (optional)',
+		color_label: 'Color (optional)',
+		create: 'Create deck',
+		creating: 'Creating…',
+		cancel: 'Cancel',
+		create_failed: 'Create failed: {msg}',
+	},
+	card_new: {
+		title: 'New card',
+		back: '← Back',
+		deck_label: 'Deck',
+		type_label: 'Type',
+		type_basic: 'Basic (front → back)',
+		type_basic_reverse: 'Basic + Reverse (front ↔ back, 2 reviews)',
+		type_cloze: 'Cloze (fill-in-the-blank, 1 review per cluster)',
+		front_label: 'Front (Markdown)',
+		back_label: 'Back (Markdown)',
+		back_placeholder: 'Answer',
+		front_placeholder: '# Markdown is allowed\n**bold**, _italic_, `code`',
+		preview_label: 'Preview',
+		cloze_text_label: 'Text with blanks (Markdown)',
+		cloze_text_placeholder: 'The capital of {{c1::France}} is {{c2::Paris}}.',
+		cloze_help: '{{c1::Answer}} defines a blank. Each cluster ID (c1, c2, …) becomes its own review.',
+		cloze_no_clusters: 'At least one {{cN::…}} cluster is required.',
+		cloze_clusters_detected: '{n} clusters detected: c{ids} → {n} reviews.',
+		cloze_preview_label: 'Preview (c{first} masked)',
+		cloze_extra_label: 'Extra (optional)',
+		cloze_extra_placeholder: 'Additional context, shown below the answer.',
+		create: 'Create card',
+		creating: 'Saving…',
+		cancel: 'Cancel',
+		create_failed: 'Create failed: {msg}',
+		toast_basic: 'Card created',
+		toast_basic_reverse: '2 reviews initialized (front→back, back→front)',
+		toast_cloze: '{n} reviews initialized (1 per cluster)',
+		decks_load_failed: 'Could not load decks: {msg}',
+	},
+	card_edit: {
+		title: 'Edit card',
+		back: '← Back to deck',
+		type_locked_help: 'The card type cannot be changed — the reviews table depends on it.',
+		save: 'Save',
+		saving: 'Saving…',
+		cancel: 'Cancel',
+		delete: 'Delete',
+		deleting: 'Deleting…',
+		delete_confirm: 'Really delete card? Reviews will be deleted with it.',
+		updated: 'Card updated',
+		save_failed: 'Save failed: {msg}',
+		delete_failed: 'Delete failed: {msg}',
+		deleted: 'Card deleted',
+	},
+	study: {
+		title: 'Study',
+		empty: 'No decks.',
+		none_due: 'Nothing due right now.',
+		study_now: 'Study now',
+		due_count: '{n} due',
+	},
+	study_session: {
+		back: '← Overview',
+		all_done: 'Done! All due cards reviewed.',
+		stats: 'Reviews: {reviewed} · Again: {again}',
+		reveal: 'Show answer',
+		reveal_hint: 'Space / Enter to reveal',
+		grade_again: 'Again',
+		grade_hard: 'Hard',
+		grade_good: 'Good',
+		grade_easy: 'Easy',
+		grade_hint: '1=Again · 2=Hard · 3=Good · 4=Easy',
+		loading: 'Loading…',
+		error: 'Error: {msg}',
+	},
+	import: {
+		title: 'Import',
+		intro: 'Import decks and cards from an Anki file (.apkg or .colpkg). FSRS history is not carried over — all cards start as "new".',
+		what_works_title: 'What is imported',
+		what_works_decks: 'Decks (Anki hierarchy Foo::Bar becomes Foo / Bar).',
+		what_works_basic: 'Basic + Basic-Reverse: front/back directly.',
+		what_works_cloze: 'Cloze: {{c1::…}} is created with sub-index per cluster.',
+		what_skipped_title: 'What is not imported',
+		what_skipped_media: 'Images + audio (will arrive with the platform integration in a later phase).',
+		what_skipped_history: 'FSRS learning history (Anki reviews are deliberately reset).',
+		what_skipped_addons: 'Add-on specific card types (image-occlusion etc.).',
+		anki_label: 'Import from Anki',
+		dropzone: '📦 Drop .apkg file here or click',
+		dropzone_hint: 'Basic, Basic + Reverse, Cloze · Images + audio are not imported in this phase.',
+		parsing: 'Reading {file}…',
+		preview_found: 'Found in',
+		preview_decks_one: '1 deck',
+		preview_decks: '{n} decks',
+		preview_cards_one: '1 card',
+		preview_cards: '{n} cards',
+		preview_breakdown: '({basic} basic, {basic_reverse} basic-reverse, {cloze} cloze)',
+		preview_media: '{n} media files (will NOT be imported in this phase)',
+		preview_skipped: '{n} skipped (unknown type)',
+		preview_warnings: 'Notes ({n})',
+		cancel: 'Cancel',
+		import_now: 'Import',
+		stage_decks: 'Creating decks · {current} / {total}',
+		stage_cards: 'Importing cards · {current} / {total}',
+		stage_done: 'Done.',
+		done_summary_one: '✓ {cards} cards in 1 deck.',
+		done_summary: '✓ {cards} cards in {decks} decks.',
+		done_failures: '{n} errors',
+		done_more: 'Another file',
+		error_label: 'Error: {msg}',
+		retry: 'Try again',
+	},
+	inbox_banner: {
+		label: '📥 Inbox',
+		count_one: '1 incoming card from other apps',
+		count: '{n} incoming cards from other apps',
+		cta: '— sort →',
+	},
+	account: {
+		title: 'Account',
+		user_id_label: 'User ID',
+		logout: 'Sign out',
+		phase2_hint:
+			'Phase 2 note: identity is currently a dev stub (sessionStorage). With auth federation, this switches to a mana-auth login against auth.mana.how.',
+		export_title: 'Data export',
+		export_intro:
+			'Download all your Cards data as JSON — decks, cards, reviews, study sessions, tags, media refs, import jobs. GDPR Art. 15/20.',
+		export_button: 'Export data',
+		export_loading: 'Loading…',
+		export_done: 'Export downloaded: {decks} decks, {cards} cards, {reviews} reviews.',
+		export_failed: 'Export failed: {msg}',
+		delete_title: 'Delete account',
+		delete_intro:
+			'Irreversibly deletes all your Cards data. GDPR Art. 17. Other mana apps (Memoro, Who, …) keep their data independently — if you want to delete there too, do it there or use the Verein-wide GDPR collective request via mana-admin.',
+		delete_button: 'Delete all Cards data',
+		delete_loading: 'Deleting…',
+		delete_confirm:
+			'ALL your Cards data will be deleted irreversibly. Type DELETE to confirm.',
+		delete_confirm_word: 'DELETE',
+		delete_done: 'Deleted: {decks} decks, {imports} import jobs.',
+		delete_failed: 'Delete failed: {msg}',
+	},
+	stats: {
+		title: 'Stats',
+		generated_at: 'As of {date}',
+		decks: 'Decks',
+		cards: 'Cards',
+		reviews: 'Reviews',
+		due_now: 'Due now',
+		days_title: 'Active days',
+		streak: 'Streak: {n} days · last 7 days: {total} reviews',
+		streak_one: 'Streak: 1 day · last 7 days: {total} reviews',
+		fsrs_title: 'FSRS status',
+		fsrs_intro: 'Distribution of your card reviews across FSRS states.',
+		fsrs_new: 'New',
+		fsrs_learning: 'Learning',
+		fsrs_review: 'Review',
+		fsrs_relearning: 'Relearning',
+		loading: 'Loading…',
+		error: 'Error: {msg}',
+	},
+	common: {
+		empty: '(empty)',
+	},
+};
diff --git a/apps/web/src/lib/i18n/index.svelte.ts b/apps/web/src/lib/i18n/index.svelte.ts
new file mode 100644
index 0000000..4814dff
--- /dev/null
+++ b/apps/web/src/lib/i18n/index.svelte.ts
@@ -0,0 +1,91 @@
+/**
+ * Schmaler i18n-Core. Eigenbau statt svelte-i18n, weil:
+ *  - 2 Sprachen, ~150 Strings → keine Compile-Time-Type-Safety nötig
+ *  - keine Pluralregeln (`_one` als manueller Fallback reicht)
+ *  - keine Server-Side-Lade-Komplexität (alles eager, ~3kB)
+ *
+ * Locale wird in localStorage persistiert, Default = navigator.language
+ * (DE/EN), Fallback = de.
+ */
+
+import { de, type TranslationNode } from './de.ts';
+import { en } from './en.ts';
+
+export type Locale = 'de' | 'en';
+
+const TRANSLATIONS: Record<Locale, TranslationNode> = { de, en };
+const STORAGE_KEY = 'cards.locale';
+
+function detectInitial(): Locale {
+	if (typeof window === 'undefined') return 'de';
+	const stored = window.localStorage.getItem(STORAGE_KEY);
+	if (stored === 'de' || stored === 'en') return stored;
+	const nav = window.navigator?.language ?? '';
+	return nav.toLowerCase().startsWith('en') ? 'en' : 'de';
+}
+
+class I18nState {
+	current = $state<Locale>('de');
+
+	constructor() {
+		// onMount-äquivalent: nur in der Browser-Phase initialisieren.
+		if (typeof window !== 'undefined') {
+			this.current = detectInitial();
+		}
+	}
+
+	set(locale: Locale) {
+		this.current = locale;
+		if (typeof window !== 'undefined') {
+			window.localStorage.setItem(STORAGE_KEY, locale);
+			document.documentElement.setAttribute('lang', locale);
+		}
+	}
+}
+
+export const i18n = new I18nState();
+
+/**
+ * Resolve dotted key against the current locale tree. Returns the key
+ * itself on miss so missing strings are obvious in the UI rather than
+ * silently empty.
+ */
+function resolve(locale: Locale, key: string): string {
+	const parts = key.split('.');
+	let cur: unknown = TRANSLATIONS[locale];
+	for (const p of parts) {
+		if (cur && typeof cur === 'object' && p in (cur as Record<string, unknown>)) {
+			cur = (cur as Record<string, unknown>)[p];
+		} else {
+			return key;
+		}
+	}
+	return typeof cur === 'string' ? cur : key;
+}
+
+function interpolate(template: string, vars: Record<string, string | number> = {}): string {
+	return template.replace(/\{(\w+)\}/g, (_, k: string) => {
+		const v = vars[k];
+		return v === undefined ? `{${k}}` : String(v);
+	});
+}
+
+/**
+ * Translation helper. Use as `t('decks.title')` for plain strings or
+ * `t('decks.error', { msg })` for interpolation. Reads `i18n.current`
+ * reactively — Svelte runes recompute when the locale changes.
+ */
+export function t(key: string, vars?: Record<string, string | number>): string {
+	const raw = resolve(i18n.current, key);
+	return vars ? interpolate(raw, vars) : raw;
+}
+
+/**
+ * Plural-Helper — minimal: liefert `<key>_one` für n=1, sonst `<key>`.
+ * Beide Schlüssel müssen im Locale existieren. Reicht für DE/EN-MVP,
+ * komplexere Pluralregeln (FR/IT/PL) brauchen später Intl.PluralRules.
+ */
+export function tn(baseKey: string, n: number, vars?: Record<string, string | number>): string {
+	const key = n === 1 ? `${baseKey}_one` : baseKey;
+	return t(key, { ...(vars ?? {}), n });
+}
diff --git a/apps/web/src/routes/+page.svelte b/apps/web/src/routes/+page.svelte
index eb4a266..c6e0590 100644
--- a/apps/web/src/routes/+page.svelte
+++ b/apps/web/src/routes/+page.svelte
@@ -2,6 +2,7 @@
 	import { onMount } from 'svelte';
 	import { goto } from '$app/navigation';
 	import { devUser } from '$lib/auth/dev-stub.svelte.ts';
+	import { t } from '$lib/i18n/index.svelte.ts';
 
 	onMount(() => {
 		if (devUser.id) goto('/decks');
@@ -9,20 +10,15 @@
 </script>
 
 <div class="mx-auto max-w-2xl py-12 text-center">
-	<h1 class="text-3xl font-semibold">Cards</h1>
-	<p class="mt-2 text-[var(--color-muted)]">
-		Karteikarten-App des Vereins <strong>mana e.V.</strong>
-	</p>
+	<h1 class="text-3xl font-semibold">{t('app.name')}</h1>
+	<p class="mt-2 text-[var(--color-muted)]">{t('landing.welcome')}</p>
+	<p class="mt-1 text-sm text-[var(--color-muted)]">{t('landing.intro')}</p>
 
 	{#if !devUser.id}
 		<div
 			class="mt-8 rounded-lg border bg-[var(--color-card)] border-[var(--color-border)] p-6 text-left"
 		>
-			<h2 class="text-lg font-medium">Phase 0 — Dev-Login</h2>
-			<p class="mt-1 text-sm text-[var(--color-muted)]">
-				Bevor mana-auth-Föderation steht (Phase 2), schaltet ein Dev-Stub den Login frei.
-				Trag eine User-ID ein (z.B. <code>u-test-1</code>).
-			</p>
+			<h2 class="text-lg font-medium">{t('landing.cta_login')}</h2>
 			<form
 				class="mt-4 flex gap-2"
 				onsubmit={(e) => {
@@ -38,12 +34,13 @@
 				<input
 					name="user_id"
 					placeholder="u-test-1"
+					aria-label={t('landing.dev_user_prompt')}
 					class="flex-1 rounded border bg-[var(--color-bg)] border-[var(--color-border)] px-3 py-2 text-sm"
 					required
 				/>
 				<button
 					class="rounded bg-[var(--color-primary)] px-4 py-2 text-sm text-[var(--color-primary-fg)]"
-					type="submit">Weiter</button
+					type="submit">→</button
 				>
 			</form>
 		</div>
diff --git a/apps/web/src/routes/account/+page.svelte b/apps/web/src/routes/account/+page.svelte
index 71d39cf..60cd1ec 100644
--- a/apps/web/src/routes/account/+page.svelte
+++ b/apps/web/src/routes/account/+page.svelte
@@ -3,25 +3,14 @@
 	import { goto } from '$app/navigation';
 	import { devUser } from '$lib/auth/dev-stub.svelte.ts';
 	import { exportMe, deleteMe } from '$lib/api/me.ts';
-	import { listDecks } from '$lib/api/decks.ts';
 	import { toasts } from '$lib/stores/toasts.svelte.ts';
+	import { t } from '$lib/i18n/index.svelte.ts';
 
-	let stats = $state<{ decks: number; cards: number } | null>(null);
 	let exporting = $state(false);
 	let deleting = $state(false);
 
-	onMount(async () => {
-		if (!devUser.id) {
-			goto('/');
-			return;
-		}
-		try {
-			const r = await listDecks();
-			const cards = r.decks.reduce((sum) => sum, 0); // listDecks returns total decks; cards via separate calls
-			stats = { decks: r.total, cards };
-		} catch {
-			stats = null;
-		}
+	onMount(() => {
+		if (!devUser.id) goto('/');
 	});
 
 	async function onExport() {
@@ -38,28 +27,30 @@
 			a.remove();
 			URL.revokeObjectURL(url);
 			toasts.success(
-				`Export geladen: ${data.data.decks.length} Decks, ${data.data.cards.length} Karten, ${data.data.reviews.length} Reviews.`
+				t('account.export_done', {
+					decks: data.data.decks.length,
+					cards: data.data.cards.length,
+					reviews: data.data.reviews.length,
+				})
 			);
 		} catch (e) {
-			toasts.error(`Export fehlgeschlagen: ${(e as Error).message}`);
+			toasts.error(t('account.export_failed', { msg: (e as Error).message }));
 		} finally {
 			exporting = false;
 		}
 	}
 
 	async function onDelete() {
-		const confirmation = prompt(
-			'ALLE deine Cards-Daten werden unwiderruflich gelöscht. Tippe LÖSCHEN zur Bestätigung.'
-		);
-		if (confirmation !== 'LÖSCHEN') return;
+		const confirmation = prompt(t('account.delete_confirm'));
+		if (confirmation !== t('account.delete_confirm_word')) return;
 		deleting = true;
 		try {
 			const r = await deleteMe();
-			toasts.success(`Gelöscht: ${r.counts.decks} Decks, ${r.counts.import_jobs} Import-Jobs.`);
+			toasts.success(t('account.delete_done', { decks: r.counts.decks, imports: r.counts.import_jobs }));
 			devUser.clear();
 			goto('/');
 		} catch (e) {
-			toasts.error(`Löschen fehlgeschlagen: ${(e as Error).message}`);
+			toasts.error(t('account.delete_failed', { msg: (e as Error).message }));
 			deleting = false;
 		}
 	}
@@ -71,15 +62,15 @@
 </script>
 
 <svelte:head>
-	<title>Account · Cards</title>
+	<title>{t('account.title')} · {t('app.title_suffix')}</title>
 </svelte:head>
 
 <div class="mx-auto max-w-2xl px-4 py-8">
-	<h1 class="text-2xl font-semibold">Account</h1>
+	<h1 class="text-2xl font-semibold">{t('account.title')}</h1>
 
 	<section class="mt-6 rounded-lg border border-[var(--color-border)] bg-[var(--color-card)] p-4">
 		<div class="text-sm">
-			<div class="text-[var(--color-muted)]">User-ID</div>
+			<div class="text-[var(--color-muted)]">{t('account.user_id_label')}</div>
 			<code class="mt-1 block break-all text-sm">{devUser.id ?? '—'}</code>
 		</div>
 		<div class="mt-3 flex gap-3">
@@ -88,45 +79,35 @@
 				onclick={logout}
 				class="rounded border border-[var(--color-border)] px-3 py-1.5 text-sm hover:bg-[var(--color-border)]/40"
 			>
-				Abmelden
+				{t('account.logout')}
 			</button>
 		</div>
-		<p class="mt-3 text-xs text-[var(--color-muted)]">
-			Phase-2-Hinweis: aktuell ist die Identität ein Dev-Stub (sessionStorage). Mit Auth-Föderation
-			wechselt das auf einen mana-auth-Login gegen <code>auth.mana.how</code>.
-		</p>
+		<p class="mt-3 text-xs text-[var(--color-muted)]">{t('account.phase2_hint')}</p>
 	</section>
 
 	<section class="mt-6 rounded-lg border border-[var(--color-border)] bg-[var(--color-card)] p-4">
-		<h2 class="text-lg font-medium">Daten-Export</h2>
-		<p class="mt-1 text-sm text-[var(--color-muted)]">
-			Lade alle deine Cards-Daten als JSON herunter — Decks, Karten, Reviews, Study-Sessions, Tags,
-			Media-Refs, Import-Jobs. DSGVO Art. 15/20.
-		</p>
+		<h2 class="text-lg font-medium">{t('account.export_title')}</h2>
+		<p class="mt-1 text-sm text-[var(--color-muted)]">{t('account.export_intro')}</p>
 		<button
 			type="button"
 			onclick={onExport}
 			disabled={exporting}
 			class="mt-3 rounded bg-[var(--color-primary)] px-4 py-1.5 text-sm text-[var(--color-primary-fg)] disabled:opacity-50"
 		>
-			{exporting ? 'Lade…' : 'Daten exportieren'}
+			{exporting ? t('account.export_loading') : t('account.export_button')}
 		</button>
 	</section>
 
 	<section class="mt-6 rounded-lg border border-[var(--color-danger)]/30 bg-[var(--color-card)] p-4">
-		<h2 class="text-lg font-medium text-[var(--color-danger)]">Konto löschen</h2>
-		<p class="mt-1 text-sm text-[var(--color-muted)]">
-			Löscht unwiderruflich alle deine Cards-Daten. DSGVO Art. 17. Andere mana-Apps (Memoro, Who, …)
-			behalten ihre Daten unabhängig — wenn du dort auch löschen willst, mach das jeweils dort oder
-			nutze die Verein-DSGVO-Sammelanfrage über mana-admin.
-		</p>
+		<h2 class="text-lg font-medium text-[var(--color-danger)]">{t('account.delete_title')}</h2>
+		<p class="mt-1 text-sm text-[var(--color-muted)]">{t('account.delete_intro')}</p>
 		<button
 			type="button"
 			onclick={onDelete}
 			disabled={deleting}
 			class="mt-3 rounded border border-[var(--color-danger)] px-4 py-1.5 text-sm text-[var(--color-danger)] hover:bg-[var(--color-danger)]/10 disabled:opacity-50"
 		>
-			{deleting ? 'Lösche…' : 'Alle Cards-Daten löschen'}
+			{deleting ? t('account.delete_loading') : t('account.delete_button')}
 		</button>
 	</section>
 </div>
diff --git a/apps/web/src/routes/cards/[id]/edit/+page.svelte b/apps/web/src/routes/cards/[id]/edit/+page.svelte
index ea10954..bb10b26 100644
--- a/apps/web/src/routes/cards/[id]/edit/+page.svelte
+++ b/apps/web/src/routes/cards/[id]/edit/+page.svelte
@@ -12,6 +12,7 @@
 	import { devUser } from '$lib/auth/dev-stub.svelte.ts';
 	import { renderMarkdown } from '$lib/markdown.ts';
 	import { toasts } from '$lib/stores/toasts.svelte.ts';
+	import { t } from '$lib/i18n/index.svelte.ts';
 
 	let card = $state<Card | null>(null);
 	let cardType = $state<CardType>('basic');
@@ -78,76 +79,71 @@
 						: { text: text.trim() }
 					: { front: front.trim(), back: back.trim() };
 			const updated = await updateCard(card.id, { fields });
-			toasts.success('Karte aktualisiert');
+			toasts.success(t('card_edit.updated'));
 			goto(`/decks/${updated.deck_id}`);
 		} catch (e) {
-			toasts.error(`Speichern fehlgeschlagen: ${(e as Error).message}`);
+			toasts.error(t('card_edit.save_failed', { msg: (e as Error).message }));
 			saving = false;
 		}
 	}
 
 	async function onDelete() {
 		if (!card) return;
-		if (!confirm('Karte wirklich löschen? Reviews werden mit gelöscht.')) return;
+		if (!confirm(t('card_edit.delete_confirm'))) return;
 		try {
 			await deleteCard(card.id);
-			toasts.success('Karte gelöscht');
+			toasts.success(t('card_edit.deleted'));
 			goto(`/decks/${card.deck_id}`);
 		} catch (e) {
-			toasts.error(`Löschen fehlgeschlagen: ${(e as Error).message}`);
+			toasts.error(t('card_edit.delete_failed', { msg: (e as Error).message }));
 		}
 	}
 </script>
 
 <svelte:head>
-	<title>Karte bearbeiten · Cards</title>
+	<title>{t('card_edit.title')} · {t('app.title_suffix')}</title>
 </svelte:head>
 
 <div class="mx-auto max-w-3xl px-4 py-6">
 	{#if loading}
-		<p class="text-[var(--color-muted)]">Lade…</p>
+		<p class="text-[var(--color-muted)]">{t('decks.loading')}</p>
 	{:else if error}
-		<p class="text-[var(--color-danger)]">Fehler: {error}</p>
+		<p class="text-[var(--color-danger)]">{t('decks.error', { msg: error })}</p>
 	{:else if card}
 		<a
 			href="/decks/{card.deck_id}"
-			class="text-sm text-[var(--color-muted)] hover:text-[var(--color-fg)]">← Zurück zum Deck</a
+			class="text-sm text-[var(--color-muted)] hover:text-[var(--color-fg)]">{t('card_edit.back')}</a
 		>
 		<div class="mt-2 flex items-baseline justify-between gap-3">
-			<h1 class="text-2xl font-semibold">Karte bearbeiten</h1>
+			<h1 class="text-2xl font-semibold">{t('card_edit.title')}</h1>
 			<span class="rounded bg-[var(--color-border)] px-2 py-0.5 text-xs text-[var(--color-muted)]">
 				{cardType}
 			</span>
 		</div>
-		<p class="mt-1 text-xs text-[var(--color-muted)]">
-			Der Card-Type kann nicht geändert werden — die Reviews-Tabelle hängt am Type.
-		</p>
+		<p class="mt-1 text-xs text-[var(--color-muted)]">{t('card_edit.type_locked_help')}</p>
 
 		<form class="mt-6 space-y-5" onsubmit={onSubmit}>
 			{#if cardType === 'cloze'}
 				<div>
 					<label class="block">
-						<span class="text-sm font-medium">Text mit Lücken (Markdown)</span>
+						<span class="text-sm font-medium">{t('card_new.cloze_text_label')}</span>
 						<textarea
 							bind:value={text}
 							required
 							rows="6"
-							placeholder="Die Hauptstadt von {'{{c1::Frankreich}}'} ist {'{{c2::Paris}}'}."
+							placeholder={t('card_new.cloze_text_placeholder')}
 							class="mt-1 block w-full rounded border bg-[var(--color-card)] border-[var(--color-border)] px-3 py-2 font-mono text-sm"
 						></textarea>
 					</label>
-					<p class="mt-1 text-xs text-[var(--color-muted)]">
-						<code>{'{{c1::Antwort}}'}</code> definiert eine Lücke. Pro Cluster-ID
-						(<code>c1</code>, <code>c2</code>, …) entsteht ein eigenes Review.
-					</p>
+					<p class="mt-1 text-xs text-[var(--color-muted)]">{t('card_new.cloze_help')}</p>
 					{#if text.trim() && clusterIds.length === 0}
-						<p class="mt-1 text-xs text-[var(--color-danger)]">
-							Mindestens ein <code>{'{{cN::…}}'}</code>-Cluster wird gebraucht.
-						</p>
+						<p class="mt-1 text-xs text-[var(--color-danger)]">{t('card_new.cloze_no_clusters')}</p>
 					{:else if clusterIds.length > 0}
 						<p class="mt-1 text-xs text-[var(--color-muted)]">
-							{clusterIds.length} Cluster erkannt: c{clusterIds.join(', c')} → {clusterIds.length}
-							Reviews.
+							{t('card_new.cloze_clusters_detected', {
+								n: clusterIds.length,
+								ids: clusterIds.join(', c'),
+							})}
 						</p>
 					{/if}
 				</div>
@@ -155,18 +151,18 @@
 				{#if clozePreviewHtml}
 					<div class="rounded border border-[var(--color-border)] bg-[var(--color-card)] p-3 text-sm">
 						<div class="mb-1 text-xs uppercase text-[var(--color-muted)]">
-							Vorschau (c{clusterIds[0]} maskiert)
+							{t('card_new.cloze_preview_label', { first: clusterIds[0] ?? 1 })}
 						</div>
 						<div class="prose prose-sm max-w-none">{@html clozePreviewHtml}</div>
 					</div>
 				{/if}
 
 				<label class="block">
-					<span class="text-sm font-medium">Extra (optional)</span>
+					<span class="text-sm font-medium">{t('card_new.cloze_extra_label')}</span>
 					<textarea
 						bind:value={extra}
 						rows="3"
-						placeholder="Zusätzlicher Kontext, wird unter der Antwort gezeigt."
+						placeholder={t('card_new.cloze_extra_placeholder')}
 						class="mt-1 block w-full rounded border bg-[var(--color-card)] border-[var(--color-border)] px-3 py-2 font-mono text-sm"
 					></textarea>
 				</label>
@@ -174,7 +170,7 @@
 				<div class="grid grid-cols-1 gap-4 sm:grid-cols-2">
 					<div>
 						<label class="block">
-							<span class="text-sm font-medium">Vorderseite (Markdown)</span>
+							<span class="text-sm font-medium">{t('card_new.front_label')}</span>
 							<textarea
 								bind:value={front}
 								required
@@ -184,14 +180,14 @@
 						</label>
 						{#if front.trim()}
 							<div class="mt-2 rounded border border-[var(--color-border)] bg-[var(--color-card)] p-3 text-sm">
-								<div class="mb-1 text-xs uppercase text-[var(--color-muted)]">Vorschau</div>
+								<div class="mb-1 text-xs uppercase text-[var(--color-muted)]">{t('card_new.preview_label')}</div>
 								<div class="prose prose-sm max-w-none">{@html frontHtml}</div>
 							</div>
 						{/if}
 					</div>
 					<div>
 						<label class="block">
-							<span class="text-sm font-medium">Rückseite (Markdown)</span>
+							<span class="text-sm font-medium">{t('card_new.back_label')}</span>
 							<textarea
 								bind:value={back}
 								required
@@ -201,7 +197,7 @@
 						</label>
 						{#if back.trim()}
 							<div class="mt-2 rounded border border-[var(--color-border)] bg-[var(--color-card)] p-3 text-sm">
-								<div class="mb-1 text-xs uppercase text-[var(--color-muted)]">Vorschau</div>
+								<div class="mb-1 text-xs uppercase text-[var(--color-muted)]">{t('card_new.preview_label')}</div>
 								<div class="prose prose-sm max-w-none">{@html backHtml}</div>
 							</div>
 						{/if}
@@ -216,11 +212,11 @@
 						disabled={!canSave}
 						class="rounded bg-[var(--color-primary)] px-4 py-2 text-sm text-[var(--color-primary-fg)] disabled:opacity-50"
 					>
-						{saving ? 'Speichere…' : 'Speichern'}
+						{saving ? t('card_edit.saving') : t('card_edit.save')}
 					</button>
 					<a
 						href="/decks/{card.deck_id}"
-						class="text-sm text-[var(--color-muted)] hover:text-[var(--color-fg)]">Abbrechen</a
+						class="text-sm text-[var(--color-muted)] hover:text-[var(--color-fg)]">{t('card_edit.cancel')}</a
 					>
 				</div>
 				<button
@@ -228,7 +224,7 @@
 					onclick={onDelete}
 					class="text-sm text-[var(--color-muted)] hover:text-[var(--color-danger)]"
 				>
-					Löschen
+					{t('card_edit.delete')}
 				</button>
 			</div>
 		</form>
diff --git a/apps/web/src/routes/cards/new/+page.svelte b/apps/web/src/routes/cards/new/+page.svelte
index 4ff7346..cb1cde7 100644
--- a/apps/web/src/routes/cards/new/+page.svelte
+++ b/apps/web/src/routes/cards/new/+page.svelte
@@ -12,6 +12,7 @@
 	import { devUser } from '$lib/auth/dev-stub.svelte.ts';
 	import { renderMarkdown } from '$lib/markdown.ts';
 	import { toasts } from '$lib/stores/toasts.svelte.ts';
+	import { t } from '$lib/i18n/index.svelte.ts';
 
 	type DeckLite = { id: string; name: string };
 
@@ -52,7 +53,7 @@
 				}
 			}
 		} catch (e) {
-			toasts.error(`Decks konnten nicht geladen werden: ${(e as Error).message}`);
+			toasts.error(t('card_new.decks_load_failed', { msg: (e as Error).message }));
 		}
 	});
 
@@ -78,28 +79,28 @@
 			const card = await createCard({ deck_id: deckId, type: cardType, fields });
 			const msg =
 				cardType === 'cloze'
-					? `${clusterIds.length} Reviews initialisiert (1 pro Cluster)`
+					? t('card_new.toast_cloze', { n: clusterIds.length })
 					: cardType === 'basic-reverse'
-						? '2 Reviews initialisiert (front→back, back→front)'
-						: 'Karte angelegt';
+						? t('card_new.toast_basic_reverse')
+						: t('card_new.toast_basic');
 			toasts.success(msg);
 			goto(`/decks/${card.deck_id}`);
 		} catch (e) {
-			toasts.error(`Anlegen fehlgeschlagen: ${(e as Error).message}`);
+			toasts.error(t('card_new.create_failed', { msg: (e as Error).message }));
 			saving = false;
 		}
 	}
 </script>
 
 <a href={deckId ? `/decks/${deckId}` : '/decks'} class="text-sm text-[var(--color-muted)] hover:text-[var(--color-fg)]"
-	>← Zurück</a
+	>{t('card_new.back')}</a
 >
-<h1 class="mt-2 text-2xl font-semibold">Neue Karte</h1>
+<h1 class="mt-2 text-2xl font-semibold">{t('card_new.title')}</h1>
 
 <form class="mt-6 space-y-5" onsubmit={onSubmit}>
 	<div class="grid grid-cols-1 gap-4 sm:grid-cols-2">
 		<label class="block">
-			<span class="text-sm font-medium">Deck</span>
+			<span class="text-sm font-medium">{t('card_new.deck_label')}</span>
 			<select
 				bind:value={deckId}
 				required
@@ -112,14 +113,14 @@
 		</label>
 
 		<label class="block">
-			<span class="text-sm font-medium">Typ</span>
+			<span class="text-sm font-medium">{t('card_new.type_label')}</span>
 			<select
 				bind:value={cardType}
 				class="mt-1 block w-full rounded border bg-[var(--color-card)] border-[var(--color-border)] px-3 py-2 text-sm"
 			>
-				<option value="basic">Basic (front → back)</option>
-				<option value="basic-reverse">Basic + Reverse (front ↔ back, 2 Reviews)</option>
-				<option value="cloze">Cloze (Lückentext, 1 Review pro Cluster)</option>
+				<option value="basic">{t('card_new.type_basic')}</option>
+				<option value="basic-reverse">{t('card_new.type_basic_reverse')}</option>
+				<option value="cloze">{t('card_new.type_cloze')}</option>
 			</select>
 		</label>
 	</div>
@@ -127,27 +128,24 @@
 	{#if cardType === 'cloze'}
 		<div>
 			<label class="block">
-				<span class="text-sm font-medium">Text mit Lücken (Markdown)</span>
+				<span class="text-sm font-medium">{t('card_new.cloze_text_label')}</span>
 				<textarea
 					bind:value={text}
 					required
 					rows="6"
-					placeholder="Die Hauptstadt von {'{{c1::Frankreich}}'} ist {'{{c2::Paris}}'}."
+					placeholder={t('card_new.cloze_text_placeholder')}
 					class="mt-1 block w-full rounded border bg-[var(--color-card)] border-[var(--color-border)] px-3 py-2 font-mono text-sm"
 				></textarea>
 			</label>
-			<p class="mt-1 text-xs text-[var(--color-muted)]">
-				<code>{'{{c1::Antwort}}'}</code> definiert eine Lücke. Pro Cluster-ID
-				(<code>c1</code>, <code>c2</code>, …) entsteht ein eigenes Review.
-			</p>
+			<p class="mt-1 text-xs text-[var(--color-muted)]">{t('card_new.cloze_help')}</p>
 			{#if text.trim() && clusterIds.length === 0}
-				<p class="mt-1 text-xs text-[var(--color-danger)]">
-					Mindestens ein <code>{'{{cN::…}}'}</code>-Cluster wird gebraucht.
-				</p>
+				<p class="mt-1 text-xs text-[var(--color-danger)]">{t('card_new.cloze_no_clusters')}</p>
 			{:else if clusterIds.length > 0}
 				<p class="mt-1 text-xs text-[var(--color-muted)]">
-					{clusterIds.length} Cluster erkannt: c{clusterIds.join(', c')} → {clusterIds.length}
-					Reviews.
+					{t('card_new.cloze_clusters_detected', {
+						n: clusterIds.length,
+						ids: clusterIds.join(', c'),
+					})}
 				</p>
 			{/if}
 		</div>
@@ -155,18 +153,18 @@
 		{#if clozePreviewHtml}
 			<div class="rounded border border-[var(--color-border)] bg-[var(--color-card)] p-3 text-sm">
 				<div class="mb-1 text-xs uppercase text-[var(--color-muted)]">
-					Vorschau (c{clusterIds[0]} maskiert)
+					{t('card_new.cloze_preview_label', { first: clusterIds[0] ?? 1 })}
 				</div>
 				<div class="prose prose-sm max-w-none">{@html clozePreviewHtml}</div>
 			</div>
 		{/if}
 
 		<label class="block">
-			<span class="text-sm font-medium">Extra (optional)</span>
+			<span class="text-sm font-medium">{t('card_new.cloze_extra_label')}</span>
 			<textarea
 				bind:value={extra}
 				rows="3"
-				placeholder="Zusätzlicher Kontext, wird unter der Antwort gezeigt."
+				placeholder={t('card_new.cloze_extra_placeholder')}
 				class="mt-1 block w-full rounded border bg-[var(--color-card)] border-[var(--color-border)] px-3 py-2 font-mono text-sm"
 			></textarea>
 		</label>
@@ -174,18 +172,18 @@
 		<div class="grid grid-cols-1 gap-4 sm:grid-cols-2">
 			<div>
 				<label class="block">
-					<span class="text-sm font-medium">Vorderseite (Markdown)</span>
+					<span class="text-sm font-medium">{t('card_new.front_label')}</span>
 					<textarea
 						bind:value={front}
 						required
 						rows="8"
-						placeholder="# Markdown ist erlaubt&#10;**fett**, _kursiv_, `code`"
+						placeholder={t('card_new.front_placeholder')}
 						class="mt-1 block w-full rounded border bg-[var(--color-card)] border-[var(--color-border)] px-3 py-2 font-mono text-sm"
 					></textarea>
 				</label>
 				{#if front.trim()}
 					<div class="mt-2 rounded border border-[var(--color-border)] bg-[var(--color-card)] p-3 text-sm">
-						<div class="mb-1 text-xs uppercase text-[var(--color-muted)]">Vorschau</div>
+						<div class="mb-1 text-xs uppercase text-[var(--color-muted)]">{t('card_new.preview_label')}</div>
 						<div class="prose prose-sm max-w-none">{@html frontHtml}</div>
 					</div>
 				{/if}
@@ -193,18 +191,18 @@
 
 			<div>
 				<label class="block">
-					<span class="text-sm font-medium">Rückseite (Markdown)</span>
+					<span class="text-sm font-medium">{t('card_new.back_label')}</span>
 					<textarea
 						bind:value={back}
 						required
 						rows="8"
-						placeholder="Antwort"
+						placeholder={t('card_new.back_placeholder')}
 						class="mt-1 block w-full rounded border bg-[var(--color-card)] border-[var(--color-border)] px-3 py-2 font-mono text-sm"
 					></textarea>
 				</label>
 				{#if back.trim()}
 					<div class="mt-2 rounded border border-[var(--color-border)] bg-[var(--color-card)] p-3 text-sm">
-						<div class="mb-1 text-xs uppercase text-[var(--color-muted)]">Vorschau</div>
+						<div class="mb-1 text-xs uppercase text-[var(--color-muted)]">{t('card_new.preview_label')}</div>
 						<div class="prose prose-sm max-w-none">{@html backHtml}</div>
 					</div>
 				{/if}
@@ -218,11 +216,11 @@
 			disabled={!canSave}
 			class="rounded bg-[var(--color-primary)] px-4 py-2 text-sm text-[var(--color-primary-fg)] disabled:opacity-50"
 		>
-			{saving ? 'Speichere…' : 'Karte anlegen'}
+			{saving ? t('card_new.creating') : t('card_new.create')}
 		</button>
 		<a
 			href={deckId ? `/decks/${deckId}` : '/decks'}
-			class="text-sm text-[var(--color-muted)] hover:text-[var(--color-fg)]">Abbrechen</a
+			class="text-sm text-[var(--color-muted)] hover:text-[var(--color-fg)]">{t('card_new.cancel')}</a
 		>
 	</div>
 </form>
diff --git a/apps/web/src/routes/decks/+page.svelte b/apps/web/src/routes/decks/+page.svelte
index 5837ce9..4f02bfd 100644
--- a/apps/web/src/routes/decks/+page.svelte
+++ b/apps/web/src/routes/decks/+page.svelte
@@ -6,6 +6,7 @@
 	import { devUser } from '$lib/auth/dev-stub.svelte.ts';
 	import { toasts } from '$lib/stores/toasts.svelte.ts';
 	import InboxBanner from '$lib/components/InboxBanner.svelte';
+	import { t } from '$lib/i18n/index.svelte.ts';
 
 	let decks = $state<Deck[]>([]);
 	let loading = $state(true);
@@ -33,25 +34,23 @@
 	}
 
 	async function onDelete(id: string, name: string) {
-		if (!confirm(`Deck "${name}" wirklich löschen? Alle Karten + Review-Daten gehen verloren.`)) {
-			return;
-		}
+		if (!confirm(t('decks.delete_confirm', { name }))) return;
 		try {
 			await deleteDeck(id);
-			toasts.success(`Deck "${name}" gelöscht`);
+			toasts.success(t('decks.deleted', { name }));
 			await refresh();
 		} catch (e) {
-			toasts.error(`Löschen fehlgeschlagen: ${(e as Error).message}`);
+			toasts.error(t('decks.delete_failed', { msg: (e as Error).message }));
 		}
 	}
 </script>
 
 <div class="flex items-center justify-between">
-	<h1 class="text-2xl font-semibold">Decks</h1>
+	<h1 class="text-2xl font-semibold">{t('decks.title')}</h1>
 	<a
 		href="/decks/new"
 		class="rounded bg-[var(--color-primary)] px-4 py-2 text-sm text-[var(--color-primary-fg)]"
-		>Neues Deck</a
+		>{t('decks.new')}</a
 	>
 </div>
 
@@ -60,16 +59,16 @@
 </div>
 
 {#if loading}
-	<p class="mt-8 text-[var(--color-muted)]">Lade…</p>
+	<p class="mt-8 text-[var(--color-muted)]">{t('decks.loading')}</p>
 {:else if error}
-	<p class="mt-8 text-[var(--color-danger)]">Fehler: {error}</p>
+	<p class="mt-8 text-[var(--color-danger)]">{t('decks.error', { msg: error })}</p>
 {:else if decks.length === 0}
 	<div
 		class="mt-8 rounded-lg border border-dashed border-[var(--color-border)] p-12 text-center"
 	>
-		<p class="text-[var(--color-muted)]">Noch keine Decks.</p>
+		<p class="text-[var(--color-muted)]">{t('decks.empty')}</p>
 		<a href="/decks/new" class="mt-4 inline-block text-[var(--color-primary)] hover:underline"
-			>Erstes Deck anlegen →</a
+			>{t('decks.empty_cta')} →</a
 		>
 	</div>
 {:else}
@@ -99,8 +98,8 @@
 				<button
 					class="absolute right-2 top-2 hidden rounded p-1 text-[var(--color-muted)] hover:bg-[var(--color-border)] hover:text-[var(--color-danger)] group-hover:block"
 					onclick={() => onDelete(deck.id, deck.name)}
-					aria-label="Deck löschen"
-					title="Deck löschen"
+					aria-label={t('decks.delete_confirm', { name: deck.name })}
+					title={t('decks.delete_confirm', { name: deck.name })}
 				>
 					🗑
 				</button>
diff --git a/apps/web/src/routes/decks/[id]/+page.svelte b/apps/web/src/routes/decks/[id]/+page.svelte
index e2feb20..bb092ee 100644
--- a/apps/web/src/routes/decks/[id]/+page.svelte
+++ b/apps/web/src/routes/decks/[id]/+page.svelte
@@ -8,6 +8,7 @@
 	import { listDueReviews } from '$lib/api/reviews.ts';
 	import { devUser } from '$lib/auth/dev-stub.svelte.ts';
 	import { toasts } from '$lib/stores/toasts.svelte.ts';
+	import { t, tn } from '$lib/i18n/index.svelte.ts';
 
 	let deck = $state<Deck | null>(null);
 	let cards = $state<Card[]>([]);
@@ -45,30 +46,34 @@
 	}
 
 	async function onDeleteCard(id: string) {
-		if (!confirm('Karte wirklich löschen?')) return;
+		if (!confirm(t('deck_detail.card_delete_confirm'))) return;
 		try {
 			await deleteCard(id);
-			toasts.success('Karte gelöscht');
+			toasts.success(t('card_edit.deleted'));
 			await refresh();
 		} catch (e) {
-			toasts.error(`Löschen fehlgeschlagen: ${(e as Error).message}`);
+			toasts.error(t('card_edit.delete_failed', { msg: (e as Error).message }));
 		}
 	}
 </script>
 
 {#if loading}
-	<p class="text-[var(--color-muted)]">Lade…</p>
+	<p class="text-[var(--color-muted)]">{t('decks.loading')}</p>
 {:else if error}
-	<p class="text-[var(--color-danger)]">Fehler: {error}</p>
+	<p class="text-[var(--color-danger)]">{t('decks.error', { msg: error })}</p>
 {:else if deck}
 	<a href="/decks" class="text-sm text-[var(--color-muted)] hover:text-[var(--color-fg)]"
-		>← Decks</a
+		>← {t('nav.decks')}</a
 	>
 
 	<div class="mt-2 flex flex-wrap items-center justify-between gap-4">
 		<div class="flex items-center gap-3">
 			{#if deck.color}
-				<span class="h-4 w-4 rounded-full" style="background:{deck.color}"></span>
+				<span
+					class="h-4 w-4 rounded-full"
+					style="background:{deck.color}"
+					aria-hidden="true"
+				></span>
 			{/if}
 			<h1 class="text-2xl font-semibold">{deck.name}</h1>
 		</div>
@@ -77,22 +82,22 @@
 				href="/cards/new?deck={deck.id}"
 				class="rounded border border-[var(--color-border)] px-3 py-2 text-sm hover:border-[var(--color-primary)]"
 			>
-				+ Karte
+				+ {t('deck_detail.new_card')}
 			</a>
 			{#if dueCount > 0}
 				<a
 					href="/study/{deck.id}"
 					class="rounded bg-[var(--color-primary)] px-4 py-2 text-sm text-[var(--color-primary-fg)]"
 				>
-					Lernen ({dueCount} fällig)
+					{t('deck_detail.study_button')} ({t('study.due_count', { n: dueCount })})
 				</a>
 			{:else}
 				<button
 					disabled
 					class="rounded bg-[var(--color-muted)] px-4 py-2 text-sm text-[var(--color-bg)] opacity-50"
-					title="Keine Karten fällig"
+					title={t('study.none_due')}
 				>
-					Lernen
+					{t('deck_detail.study_button')}
 				</button>
 			{/if}
 		</div>
@@ -103,18 +108,18 @@
 	{/if}
 
 	<div class="mt-2 text-sm text-[var(--color-muted)]">
-		{cards.length} Karte{cards.length === 1 ? '' : 'n'} · {dueCount} fällig
+		{tn('decks.card_count', cards.length)} · {t('study.due_count', { n: dueCount })}
 	</div>
 
 	{#if cards.length === 0}
 		<div
 			class="mt-8 rounded-lg border border-dashed border-[var(--color-border)] p-12 text-center"
 		>
-			<p class="text-[var(--color-muted)]">Noch keine Karten in diesem Deck.</p>
+			<p class="text-[var(--color-muted)]">{t('deck_detail.empty')}</p>
 			<a
 				href="/cards/new?deck={deck.id}"
 				class="mt-4 inline-block text-[var(--color-primary)] hover:underline"
-				>Erste Karte anlegen →</a
+				>{t('deck_detail.empty_cta')}</a
 			>
 		</div>
 	{:else}
@@ -132,19 +137,19 @@
 						</div>
 						<p class="mt-1 truncate text-sm">
 							{#if card.type === 'cloze'}
-								<span class="font-medium">{card.fields.text ?? '(leer)'}</span>
+								<span class="font-medium">{card.fields.text ?? t('common.empty')}</span>
 							{:else}
-								<span class="font-medium">{card.fields.front ?? '(leer)'}</span>
-								<span class="text-[var(--color-muted)]"> → {card.fields.back ?? '(leer)'}</span>
+								<span class="font-medium">{card.fields.front ?? t('common.empty')}</span>
+								<span class="text-[var(--color-muted)]"> → {card.fields.back ?? t('common.empty')}</span>
 							{/if}
 						</p>
 					</a>
 					<button
 						class="opacity-0 group-hover:opacity-100 text-sm text-[var(--color-muted)] hover:text-[var(--color-danger)]"
 						onclick={() => onDeleteCard(card.id)}
-						aria-label="Karte löschen"
+						aria-label={t('deck_detail.card_delete_aria')}
 					>
-						Löschen
+						{t('deck_detail.card_delete_label')}
 					</button>
 				</li>
 			{/each}
diff --git a/apps/web/src/routes/decks/new/+page.svelte b/apps/web/src/routes/decks/new/+page.svelte
index 13b88f8..87d6538 100644
--- a/apps/web/src/routes/decks/new/+page.svelte
+++ b/apps/web/src/routes/decks/new/+page.svelte
@@ -2,6 +2,7 @@
 	import { goto } from '$app/navigation';
 	import { createDeck } from '$lib/api/decks.ts';
 	import { toasts } from '$lib/stores/toasts.svelte.ts';
+	import { t } from '$lib/i18n/index.svelte.ts';
 
 	let name = $state('');
 	let description = $state('');
@@ -18,10 +19,10 @@
 				description: description.trim() || undefined,
 				color,
 			});
-			toasts.success(`Deck "${deck.name}" angelegt`);
+			toasts.success(`${deck.name} ✓`);
 			goto(`/decks/${deck.id}`);
 		} catch (e) {
-			toasts.error(`Anlegen fehlgeschlagen: ${(e as Error).message}`);
+			toasts.error(t('deck_new.create_failed', { msg: (e as Error).message }));
 			saving = false;
 		}
 	}
@@ -29,35 +30,33 @@
 
 <div class="mx-auto max-w-xl">
 	<a href="/decks" class="text-sm text-[var(--color-muted)] hover:text-[var(--color-fg)]"
-		>← Zurück</a
+		>{t('deck_detail.back')}</a
 	>
-	<h1 class="mt-2 text-2xl font-semibold">Neues Deck</h1>
+	<h1 class="mt-2 text-2xl font-semibold">{t('deck_new.title')}</h1>
 
 	<form class="mt-6 space-y-4" onsubmit={onSubmit}>
 		<label class="block">
-			<span class="text-sm font-medium">Name</span>
+			<span class="text-sm font-medium">{t('deck_new.name_label')}</span>
 			<input
 				bind:value={name}
 				required
 				maxlength="200"
-				placeholder="z.B. Konfuzius-Zitate"
 				class="mt-1 block w-full rounded border bg-[var(--color-card)] border-[var(--color-border)] px-3 py-2 text-sm"
 			/>
 		</label>
 
 		<label class="block">
-			<span class="text-sm font-medium">Beschreibung</span>
+			<span class="text-sm font-medium">{t('deck_new.description_label')}</span>
 			<textarea
 				bind:value={description}
 				maxlength="2000"
 				rows="3"
-				placeholder="Optional"
 				class="mt-1 block w-full rounded border bg-[var(--color-card)] border-[var(--color-border)] px-3 py-2 text-sm"
 			></textarea>
 		</label>
 
 		<label class="block">
-			<span class="text-sm font-medium">Farbe</span>
+			<span class="text-sm font-medium">{t('deck_new.color_label')}</span>
 			<input
 				type="color"
 				bind:value={color}
@@ -71,10 +70,10 @@
 				disabled={saving || !name.trim()}
 				class="rounded bg-[var(--color-primary)] px-4 py-2 text-sm text-[var(--color-primary-fg)] disabled:opacity-50"
 			>
-				{saving ? 'Speichere…' : 'Deck anlegen'}
+				{saving ? t('deck_new.creating') : t('deck_new.create')}
 			</button>
 			<a href="/decks" class="text-sm text-[var(--color-muted)] hover:text-[var(--color-fg)]"
-				>Abbrechen</a
+				>{t('deck_new.cancel')}</a
 			>
 		</div>
 	</form>
diff --git a/apps/web/src/routes/import/+page.svelte b/apps/web/src/routes/import/+page.svelte
index e00d086..3c18e69 100644
--- a/apps/web/src/routes/import/+page.svelte
+++ b/apps/web/src/routes/import/+page.svelte
@@ -3,6 +3,7 @@
 	import { goto } from '$app/navigation';
 	import { devUser } from '$lib/auth/dev-stub.svelte.ts';
 	import AnkiImport from '$lib/components/AnkiImport.svelte';
+	import { t } from '$lib/i18n/index.svelte.ts';
 
 	onMount(() => {
 		if (!devUser.id) {
@@ -12,32 +13,29 @@
 </script>
 
 <svelte:head>
-	<title>Import · Cards</title>
+	<title>{t('import.title')} · {t('app.title_suffix')}</title>
 </svelte:head>
 
 <div class="mx-auto max-w-2xl px-4 py-8">
-	<h1 class="text-2xl font-semibold">Importieren</h1>
-	<p class="mt-2 text-sm text-[var(--color-muted)]">
-		Übernimm Decks und Karten aus einer Anki-Datei (<code>.apkg</code> oder <code>.colpkg</code>).
-		FSRS-Verlauf wird nicht übernommen — alle Karten starten als „neu".
-	</p>
+	<h1 class="text-2xl font-semibold">{t('import.title')}</h1>
+	<p class="mt-2 text-sm text-[var(--color-muted)]">{t('import.intro')}</p>
 
 	<div class="mt-6">
 		<AnkiImport />
 	</div>
 
 	<aside class="mt-8 rounded-lg border border-dashed border-[var(--color-border)] p-4 text-xs text-[var(--color-muted)]">
-		<div class="mb-1 font-medium text-[var(--color-fg)]">Was wird übernommen</div>
+		<div class="mb-1 font-medium text-[var(--color-fg)]">{t('import.what_works_title')}</div>
 		<ul class="list-disc pl-4">
-			<li>Decks (Anki-Hierarchie <code>Foo::Bar</code> wird zu <code>Foo / Bar</code>).</li>
-			<li>Basic + Basic-Reverse: Front/Back direkt.</li>
-			<li>Cloze: <code>{'{{c1::…}}'}</code> wird mit Sub-Index pro Cluster angelegt.</li>
+			<li>{t('import.what_works_decks')}</li>
+			<li>{t('import.what_works_basic')}</li>
+			<li>{t('import.what_works_cloze')}</li>
 		</ul>
-		<div class="mt-2 mb-1 font-medium text-[var(--color-fg)]">Was nicht übernommen wird</div>
+		<div class="mt-2 mb-1 font-medium text-[var(--color-fg)]">{t('import.what_skipped_title')}</div>
 		<ul class="list-disc pl-4">
-			<li>Bilder + Audio (kommen mit der Plattform-Anbindung in einer späteren Phase).</li>
-			<li>FSRS-Lernverlauf (Anki-Reviews werden bewusst neu aufgesetzt).</li>
-			<li>Add-on-spezifische Card-Types (image-occlusion etc.).</li>
+			<li>{t('import.what_skipped_media')}</li>
+			<li>{t('import.what_skipped_history')}</li>
+			<li>{t('import.what_skipped_addons')}</li>
 		</ul>
 	</aside>
 </div>
diff --git a/apps/web/src/routes/stats/+page.svelte b/apps/web/src/routes/stats/+page.svelte
index d8545be..b2513a3 100644
--- a/apps/web/src/routes/stats/+page.svelte
+++ b/apps/web/src/routes/stats/+page.svelte
@@ -3,6 +3,7 @@
 	import { goto } from '$app/navigation';
 	import { devUser } from '$lib/auth/dev-stub.svelte.ts';
 	import { loadStats, type UserStats } from '$lib/api/me.ts';
+	import { i18n, t, tn } from '$lib/i18n/index.svelte.ts';
 
 	let stats = $state<UserStats | null>(null);
 	let loading = $state(true);
@@ -34,61 +35,71 @@
 
 	function dayLabel(iso: string): string {
 		const d = new Date(`${iso}T00:00:00Z`);
-		return d.toLocaleDateString('de-DE', { weekday: 'short' });
+		const lang = i18n.current === 'en' ? 'en-US' : 'de-DE';
+		return d.toLocaleDateString(lang, { weekday: 'short' });
+	}
+
+	function fullDate(iso: string): string {
+		const d = new Date(iso);
+		const lang = i18n.current === 'en' ? 'en-US' : 'de-DE';
+		return d.toLocaleString(lang);
 	}
 </script>
 
 <svelte:head>
-	<title>Statistik · Cards</title>
+	<title>{t('stats.title')} · {t('app.title_suffix')}</title>
 </svelte:head>
 
 <div class="mx-auto max-w-3xl px-4 py-6">
-	<h1 class="text-2xl font-semibold">Statistik</h1>
+	<h1 class="text-2xl font-semibold">{t('stats.title')}</h1>
 
 	{#if loading}
-		<p class="mt-6 text-[var(--color-muted)]">Lade…</p>
+		<p class="mt-6 text-[var(--color-muted)]">{t('stats.loading')}</p>
 	{:else if error}
-		<p class="mt-6 text-[var(--color-danger)]">Fehler: {error}</p>
+		<p class="mt-6 text-[var(--color-danger)]">{t('stats.error', { msg: error })}</p>
 	{:else if stats}
 		<p class="mt-1 text-xs text-[var(--color-muted)]">
-			Stand {new Date(stats.generated_at).toLocaleString('de-DE')}
+			{t('stats.generated_at', { date: fullDate(stats.generated_at) })}
 		</p>
 
 		<section class="mt-6 grid grid-cols-2 gap-3 sm:grid-cols-4">
 			<div class="rounded-lg border border-[var(--color-border)] bg-[var(--color-card)] p-4">
-				<div class="text-xs text-[var(--color-muted)]">Decks</div>
+				<div class="text-xs text-[var(--color-muted)]">{t('stats.decks')}</div>
 				<div class="mt-1 text-2xl font-semibold">{stats.total_decks}</div>
 			</div>
 			<div class="rounded-lg border border-[var(--color-border)] bg-[var(--color-card)] p-4">
-				<div class="text-xs text-[var(--color-muted)]">Karten</div>
+				<div class="text-xs text-[var(--color-muted)]">{t('stats.cards')}</div>
 				<div class="mt-1 text-2xl font-semibold">{stats.total_cards}</div>
 			</div>
 			<div class="rounded-lg border border-[var(--color-border)] bg-[var(--color-card)] p-4">
-				<div class="text-xs text-[var(--color-muted)]">Reviews</div>
+				<div class="text-xs text-[var(--color-muted)]">{t('stats.reviews')}</div>
 				<div class="mt-1 text-2xl font-semibold">{stats.total_reviews}</div>
 			</div>
 			<div class="rounded-lg border border-[var(--color-border)] bg-[var(--color-card)] p-4">
-				<div class="text-xs text-[var(--color-muted)]">Fällig jetzt</div>
+				<div class="text-xs text-[var(--color-muted)]">{t('stats.due_now')}</div>
 				<div class="mt-1 text-2xl font-semibold">{stats.due_now}</div>
 			</div>
 		</section>
 
 		<section class="mt-6 rounded-lg border border-[var(--color-border)] bg-[var(--color-card)] p-4">
 			<div class="flex items-baseline justify-between">
-				<h2 class="text-lg font-medium">Lerntage</h2>
+				<h2 class="text-lg font-medium">{t('stats.days_title')}</h2>
 				<span class="text-xs text-[var(--color-muted)]">
-					Streak: <strong class="text-[var(--color-fg)]">{stats.streak_days}</strong>
-					{stats.streak_days === 1 ? 'Tag' : 'Tage'} · letzte 7 Tage:
-					{reviewedTotal7} Reviews
+					{tn('stats.streak', stats.streak_days, { total: reviewedTotal7 })}
 				</span>
 			</div>
-			<div class="mt-3 flex h-32 items-end gap-2">
+			<div class="mt-3 flex h-32 items-end gap-2" role="list">
 				{#each stats.reviewed_per_day as d (d.day)}
-					<div class="flex flex-1 flex-col items-center justify-end gap-1">
+					<div
+						class="flex flex-1 flex-col items-center justify-end gap-1"
+						role="listitem"
+						aria-label="{dayLabel(d.day)}: {d.n}"
+					>
 						<div class="text-xs tabular-nums">{d.n || ''}</div>
 						<div
 							class="w-full rounded-t bg-[var(--color-primary)]/80"
 							style="height: {(d.n / peakDay) * 100}%; min-height: {d.n > 0 ? '4px' : '0'};"
+							aria-hidden="true"
 						></div>
 						<div class="text-xs text-[var(--color-muted)]">{dayLabel(d.day)}</div>
 					</div>
@@ -97,25 +108,23 @@
 		</section>
 
 		<section class="mt-6 rounded-lg border border-[var(--color-border)] bg-[var(--color-card)] p-4">
-			<h2 class="text-lg font-medium">FSRS-Status</h2>
-			<p class="mt-1 text-xs text-[var(--color-muted)]">
-				Verteilung deiner Karten-Reviews über die FSRS-Zustände.
-			</p>
+			<h2 class="text-lg font-medium">{t('stats.fsrs_title')}</h2>
+			<p class="mt-1 text-xs text-[var(--color-muted)]">{t('stats.fsrs_intro')}</p>
 			<dl class="mt-3 grid grid-cols-2 gap-3 sm:grid-cols-4">
 				<div>
-					<dt class="text-xs text-[var(--color-muted)]">Neu</dt>
+					<dt class="text-xs text-[var(--color-muted)]">{t('stats.fsrs_new')}</dt>
 					<dd class="text-xl font-semibold">{stats.state_counts.new}</dd>
 				</div>
 				<div>
-					<dt class="text-xs text-[var(--color-muted)]">Lernend</dt>
+					<dt class="text-xs text-[var(--color-muted)]">{t('stats.fsrs_learning')}</dt>
 					<dd class="text-xl font-semibold">{stats.state_counts.learning}</dd>
 				</div>
 				<div>
-					<dt class="text-xs text-[var(--color-muted)]">Review</dt>
+					<dt class="text-xs text-[var(--color-muted)]">{t('stats.fsrs_review')}</dt>
 					<dd class="text-xl font-semibold">{stats.state_counts.review}</dd>
 				</div>
 				<div>
-					<dt class="text-xs text-[var(--color-muted)]">Relearning</dt>
+					<dt class="text-xs text-[var(--color-muted)]">{t('stats.fsrs_relearning')}</dt>
 					<dd class="text-xl font-semibold">{stats.state_counts.relearning}</dd>
 				</div>
 			</dl>
diff --git a/apps/web/src/routes/study/+page.svelte b/apps/web/src/routes/study/+page.svelte
index d062be2..9e23d56 100644
--- a/apps/web/src/routes/study/+page.svelte
+++ b/apps/web/src/routes/study/+page.svelte
@@ -6,6 +6,7 @@
 	import { listDueReviews } from '$lib/api/reviews.ts';
 	import { devUser } from '$lib/auth/dev-stub.svelte.ts';
 	import InboxBanner from '$lib/components/InboxBanner.svelte';
+	import { t } from '$lib/i18n/index.svelte.ts';
 
 	type Item = { deck: Deck; due: number };
 
@@ -36,14 +37,14 @@
 	});
 </script>
 
-<h1 class="text-2xl font-semibold">Lernen</h1>
+<h1 class="text-2xl font-semibold">{t('study.title')}</h1>
 
 <div class="mt-4">
 	<InboxBanner />
 </div>
 
 {#if loading}
-	<p class="mt-8 text-[var(--color-muted)]">Lade…</p>
+	<p class="mt-8 text-[var(--color-muted)]">{t('study_session.loading')}</p>
 {:else}
 	<ul class="mt-6 space-y-2">
 		{#each items as it (it.deck.id)}
@@ -52,11 +53,15 @@
 			>
 				<div class="flex items-center gap-3 min-w-0">
 					{#if it.deck.color}
-						<span class="h-3 w-3 rounded-full" style="background:{it.deck.color}"></span>
+						<span
+							class="h-3 w-3 rounded-full"
+							style="background:{it.deck.color}"
+							aria-hidden="true"
+						></span>
 					{/if}
 					<span class="truncate font-medium">{it.deck.name}</span>
 					<span class="text-sm text-[var(--color-muted)]">
-						{it.due} fällig
+						{t('study.due_count', { n: it.due })}
 					</span>
 				</div>
 				{#if it.due > 0}
@@ -64,10 +69,10 @@
 						href="/study/{it.deck.id}"
 						class="rounded bg-[var(--color-primary)] px-3 py-1.5 text-sm text-[var(--color-primary-fg)]"
 					>
-						Starten
+						{t('study.study_now')}
 					</a>
 				{:else}
-					<span class="text-sm text-[var(--color-muted)]">—</span>
+					<span class="text-sm text-[var(--color-muted)]" aria-label={t('study.none_due')}>—</span>
 				{/if}
 			</li>
 		{/each}
diff --git a/apps/web/src/routes/study/[deckId]/+page.svelte b/apps/web/src/routes/study/[deckId]/+page.svelte
index 036664b..59c4d77 100644
--- a/apps/web/src/routes/study/[deckId]/+page.svelte
+++ b/apps/web/src/routes/study/[deckId]/+page.svelte
@@ -13,6 +13,7 @@
 	import { devUser } from '$lib/auth/dev-stub.svelte.ts';
 	import { renderMarkdown } from '$lib/markdown.ts';
 	import { toasts } from '$lib/stores/toasts.svelte.ts';
+	import { t } from '$lib/i18n/index.svelte.ts';
 
 	const deckId = $derived(page.params.deckId ?? '');
 
@@ -129,7 +130,7 @@
 			queueIndex += 1;
 			revealed = false;
 		} catch (e) {
-			toasts.error(`Speichern fehlgeschlagen: ${(e as Error).message}`);
+			toasts.error(t('card_edit.save_failed', { msg: (e as Error).message }));
 		} finally {
 			busy = false;
 		}
@@ -137,45 +138,51 @@
 </script>
 
 <div class="mx-auto max-w-2xl">
-	<a href="/study" class="text-sm text-[var(--color-muted)] hover:text-[var(--color-fg)]">← Lernen</a>
+	<a href="/study" class="text-sm text-[var(--color-muted)] hover:text-[var(--color-fg)]"
+		>{t('study_session.back')}</a
+	>
 	<h1 class="mt-2 text-xl font-semibold">{deckName}</h1>
-	<p class="mt-1 text-sm text-[var(--color-muted)]">
+	<p class="mt-1 text-sm text-[var(--color-muted)]" aria-live="polite">
 		{#if !loading && !isDone}
 			{queueIndex + 1} / {queue.length}
 		{/if}
 	</p>
 
 	{#if loading}
-		<p class="mt-12 text-center text-[var(--color-muted)]">Lade Sitzung…</p>
+		<p class="mt-12 text-center text-[var(--color-muted)]">{t('study_session.loading')}</p>
 	{:else if queue.length === 0}
 		<div class="mt-12 rounded-lg border border-dashed border-[var(--color-border)] p-12 text-center">
-			<p>Keine Karten fällig in diesem Deck. 🎉</p>
+			<p>{t('study.none_due')} 🎉</p>
 			<a href="/decks/{deckId}" class="mt-4 inline-block text-[var(--color-primary)] hover:underline">
-				Zurück zum Deck →
+				{t('card_edit.back')}
 			</a>
 		</div>
 	{:else if isDone}
 		<div class="mt-12 rounded-lg border border-[var(--color-border)] bg-[var(--color-card)] p-12 text-center">
-			<h2 class="text-xl">Sitzung abgeschlossen</h2>
+			<h2 class="text-xl">{t('study_session.all_done')}</h2>
 			<p class="mt-2 text-[var(--color-muted)]">
-				{stats.reviewed} Reviews erledigt · {stats.again}× nochmal
+				{t('study_session.stats', { reviewed: stats.reviewed, again: stats.again })}
 			</p>
 			<div class="mt-6 flex justify-center gap-3">
 				<a href="/decks/{deckId}" class="rounded border border-[var(--color-border)] px-4 py-2 text-sm">
-					Zurück zum Deck
+					{t('card_edit.back')}
 				</a>
 				<a
 					href="/study/{deckId}"
 					class="rounded bg-[var(--color-primary)] px-4 py-2 text-sm text-[var(--color-primary-fg)]"
 				>
-					Erneut prüfen
+					{t('study.study_now')}
 				</a>
 			</div>
 		</div>
 	{:else}
 		<article
 			class="mt-6 rounded-lg border border-[var(--color-border)] bg-[var(--color-card)] p-8"
+			aria-labelledby="study-prompt-heading"
 		>
+			<h2 id="study-prompt-heading" class="sr-only">
+				{revealed ? t('card_new.preview_label') : t('study_session.reveal')}
+			</h2>
 			<div class="prose prose-lg max-w-none">{@html promptHtml}</div>
 
 			{#if revealed}
@@ -190,17 +197,17 @@
 					onclick={() => (revealed = true)}
 					class="rounded bg-[var(--color-primary)] px-6 py-3 text-sm text-[var(--color-primary-fg)]"
 				>
-					Antwort zeigen <kbd class="ml-2 text-xs opacity-70">Space</kbd>
+					{t('study_session.reveal')} <kbd class="ml-2 text-xs opacity-70">Space</kbd>
 				</button>
 			</div>
 		{:else}
-			<div class="mt-6 grid grid-cols-4 gap-2">
+			<div class="mt-6 grid grid-cols-4 gap-2" role="group" aria-label={t('study_session.grade_hint')}>
 				<button
 					onclick={() => grade('again')}
 					disabled={busy}
 					class="flex flex-col items-center gap-1 rounded border border-[var(--color-danger)] bg-[var(--color-card)] px-3 py-3 text-sm disabled:opacity-50"
 				>
-					<span>Nochmal</span>
+					<span>{t('study_session.grade_again')}</span>
 					<kbd class="text-xs text-[var(--color-muted)]">1</kbd>
 				</button>
 				<button
@@ -208,7 +215,7 @@
 					disabled={busy}
 					class="flex flex-col items-center gap-1 rounded border border-[var(--color-border)] bg-[var(--color-card)] px-3 py-3 text-sm disabled:opacity-50"
 				>
-					<span>Schwer</span>
+					<span>{t('study_session.grade_hard')}</span>
 					<kbd class="text-xs text-[var(--color-muted)]">2</kbd>
 				</button>
 				<button
@@ -216,7 +223,7 @@
 					disabled={busy}
 					class="flex flex-col items-center gap-1 rounded border border-[var(--color-primary)] bg-[var(--color-primary)] px-3 py-3 text-sm text-[var(--color-primary-fg)] disabled:opacity-50"
 				>
-					<span>Gut</span>
+					<span>{t('study_session.grade_good')}</span>
 					<kbd class="text-xs opacity-70">3</kbd>
 				</button>
 				<button
@@ -224,14 +231,14 @@
 					disabled={busy}
 					class="flex flex-col items-center gap-1 rounded border border-[var(--color-success)] bg-[var(--color-card)] px-3 py-3 text-sm disabled:opacity-50"
 				>
-					<span>Leicht</span>
+					<span>{t('study_session.grade_easy')}</span>
 					<kbd class="text-xs text-[var(--color-muted)]">4</kbd>
 				</button>
 			</div>
 		{/if}
 
 		<p class="mt-6 text-center text-xs text-[var(--color-muted)]">
-			Hotkeys: <kbd>Space</kbd>/<kbd>Enter</kbd> = aufdecken &amp; gut · <kbd>1</kbd>–<kbd>4</kbd> = bewerten
+			{t('study_session.grade_hint')}
 		</p>
 	{/if}
 </div>