diff --git a/apps/api/src/db/schema/decks.ts b/apps/api/src/db/schema/decks.ts
index 71045da..0dba171 100644
--- a/apps/api/src/db/schema/decks.ts
+++ b/apps/api/src/db/schema/decks.ts
@@ -16,6 +16,21 @@ export const decks = cardsSchema.table(
 		name: text('name').notNull(),
 		description: text('description'),
 		color: text('color'),
+		category: text('category', {
+			enum: [
+				'language',
+				'medicine',
+				'science',
+				'math',
+				'history',
+				'law',
+				'technology',
+				'arts',
+				'music',
+				'sport',
+				'other',
+			],
+		}),
 		visibility: text('visibility', { enum: ['private', 'space', 'public'] })
 			.notNull()
 			.default('private'),
diff --git a/apps/api/src/db/schema/marketplace/decks.ts b/apps/api/src/db/schema/marketplace/decks.ts
index 087b31a..90a4bb5 100644
--- a/apps/api/src/db/schema/marketplace/decks.ts
+++ b/apps/api/src/db/schema/marketplace/decks.ts
@@ -53,6 +53,21 @@ export const publicDecks = marketplaceSchema.table(
 		description: text('description'),
 		// ISO-639-1 (z.B. 'de', 'en', 'es'). Nullable für mixed-language.
 		language: text('language'),
+		category: text('category', {
+			enum: [
+				'language',
+				'medicine',
+				'science',
+				'math',
+				'history',
+				'law',
+				'technology',
+				'arts',
+				'music',
+				'sport',
+				'other',
+			],
+		}),
 		// SPDX-style ID. CC0-1.0, CC-BY-4.0, CC-BY-SA-4.0,
 		// Cardecky-Personal-Use-1.0 (default für free), Cardecky-Pro-Only-1.0 (paid).
 		license: text('license').notNull().default('Cardecky-Personal-Use-1.0'),
diff --git a/apps/api/src/routes/decks.ts b/apps/api/src/routes/decks.ts
index 10d684e..0593130 100644
--- a/apps/api/src/routes/decks.ts
+++ b/apps/api/src/routes/decks.ts
@@ -37,6 +37,7 @@ export function decksRouter(deps: DecksDeps = {}): Hono<{ Variables: AuthVars }>
 				name: parsed.data.name,
 				description: parsed.data.description,
 				color: parsed.data.color,
+				category: parsed.data.category,
 				visibility: parsed.data.visibility ?? 'private',
 				fsrsSettings: parsed.data.fsrs_settings ?? {},
 				createdAt: now,
@@ -89,6 +90,7 @@ export function decksRouter(deps: DecksDeps = {}): Hono<{ Variables: AuthVars }>
 				...(parsed.data.name !== undefined && { name: parsed.data.name }),
 				...(parsed.data.description !== undefined && { description: parsed.data.description }),
 				...(parsed.data.color !== undefined && { color: parsed.data.color }),
+				...(parsed.data.category !== undefined && { category: parsed.data.category }),
 				...(parsed.data.visibility !== undefined && { visibility: parsed.data.visibility }),
 				...(parsed.data.fsrs_settings !== undefined && {
 					fsrsSettings: parsed.data.fsrs_settings,
@@ -122,6 +124,7 @@ function toDeckDto(row: typeof decks.$inferSelect) {
 		name: row.name,
 		description: row.description,
 		color: row.color,
+		category: row.category,
 		visibility: row.visibility,
 		fsrs_settings: row.fsrsSettings,
 		content_hash: row.contentHash,
diff --git a/apps/api/src/routes/marketplace/decks.ts b/apps/api/src/routes/marketplace/decks.ts
index c66aeb4..70b1331 100644
--- a/apps/api/src/routes/marketplace/decks.ts
+++ b/apps/api/src/routes/marketplace/decks.ts
@@ -41,6 +41,11 @@ export type MarketplaceDecksDeps = { db?: CardsDb };
 
 const SEMVER_RE = /^(\d+)\.(\d+)\.(\d+)$/;
 
+const MarketplaceCategorySchema = z.enum([
+	'language', 'medicine', 'science', 'math', 'history',
+	'law', 'technology', 'arts', 'music', 'sport', 'other',
+]);
+
 const InitSchema = z.object({
 	slug: z.string(),
 	title: z.string().min(1).max(120),
@@ -51,6 +56,7 @@ const InitSchema = z.object({
 		.optional(),
 	license: z.string().max(60).optional(),
 	priceCredits: z.number().int().min(0).max(100_000).optional(),
+	category: MarketplaceCategorySchema.optional(),
 });
 
 const PatchSchema = z.object({
@@ -59,6 +65,7 @@ const PatchSchema = z.object({
 	language: z.string().regex(/^[a-z]{2}$/).optional(),
 	license: z.string().max(60).optional(),
 	priceCredits: z.number().int().min(0).max(100_000).optional(),
+	category: MarketplaceCategorySchema.optional(),
 });
 
 const CardTypeSchema = z.enum([
@@ -104,6 +111,7 @@ function toDeckDto(row: typeof publicDecks.$inferSelect) {
 		title: row.title,
 		description: row.description,
 		language: row.language,
+		category: row.category,
 		license: row.license,
 		price_credits: row.priceCredits,
 		owner_user_id: row.ownerUserId,
@@ -236,6 +244,7 @@ export function marketplaceDecksRouter(
 				title: parsed.data.title,
 				description: parsed.data.description,
 				language: parsed.data.language,
+				category: parsed.data.category,
 				license,
 				priceCredits,
 				ownerUserId: userId,
@@ -275,6 +284,7 @@ export function marketplaceDecksRouter(
 				...(parsed.data.title !== undefined && { title: parsed.data.title }),
 				...(parsed.data.description !== undefined && { description: parsed.data.description }),
 				...(parsed.data.language !== undefined && { language: parsed.data.language }),
+				...(parsed.data.category !== undefined && { category: parsed.data.category }),
 				...(parsed.data.license !== undefined && { license }),
 				...(parsed.data.priceCredits !== undefined && { priceCredits }),
 			})
diff --git a/apps/api/src/routes/marketplace/explore.ts b/apps/api/src/routes/marketplace/explore.ts
index a0927f9..ba759c7 100644
--- a/apps/api/src/routes/marketplace/explore.ts
+++ b/apps/api/src/routes/marketplace/explore.ts
@@ -54,6 +54,7 @@ interface DeckListEntry {
 	title: string;
 	description: string | null;
 	language: string | null;
+	category: string | null;
 	license: string;
 	price_credits: number;
 	card_count: number;
@@ -117,6 +118,7 @@ async function browseImpl(
 			title: publicDecks.title,
 			description: publicDecks.description,
 			language: publicDecks.language,
+			category: publicDecks.category,
 			license: publicDecks.license,
 			priceCredits: publicDecks.priceCredits,
 			cardCount: cardCountExpr,
@@ -148,6 +150,7 @@ async function browseImpl(
 			title: r.title,
 			description: r.description,
 			language: r.language,
+			category: r.category,
 			license: r.license,
 			price_credits: r.priceCredits,
 			card_count: Number(r.cardCount),
diff --git a/apps/web/package.json b/apps/web/package.json
index 813e524..b522392 100644
--- a/apps/web/package.json
+++ b/apps/web/package.json
@@ -21,7 +21,8 @@
     "marked": "^18.0.3",
     "sql.js": "^1.14.1",
     "@mana/themes": "^0.1.0",
-    "@mana/shared-ui-2": "^0.1.0"
+    "@mana/shared-ui-2": "^0.1.0",
+    "@mana/shared-icons": "^1.0.0"
   },
   "devDependencies": {
     "@sveltejs/adapter-node": "^5.2.0",
diff --git a/apps/web/src/lib/api/marketplace.ts b/apps/web/src/lib/api/marketplace.ts
index 4c2f5fb..ba06f79 100644
--- a/apps/web/src/lib/api/marketplace.ts
+++ b/apps/web/src/lib/api/marketplace.ts
@@ -29,6 +29,7 @@ export interface MarketplaceDeck {
 	title: string;
 	description: string | null;
 	language: string | null;
+	category: string | null;
 	license: string;
 	price_credits: number;
 	owner_user_id: string;
@@ -61,6 +62,7 @@ export interface DeckListEntry {
 	title: string;
 	description: string | null;
 	language: string | null;
+	category: string | null;
 	license: string;
 	price_credits: number;
 	card_count: number;
diff --git a/apps/web/src/lib/components/DeckCategoryIcon.svelte b/apps/web/src/lib/components/DeckCategoryIcon.svelte
new file mode 100644
index 0000000..3ac7848
--- /dev/null
+++ b/apps/web/src/lib/components/DeckCategoryIcon.svelte
@@ -0,0 +1,47 @@
+<script lang="ts">
+	import type { DeckCategoryId } from '@cards/domain';
+	import {
+		Globe,
+		Heartbeat,
+		Leaf,
+		Brain,
+		Flag,
+		Medal,
+		Lightning,
+		Palette,
+		MusicNote,
+		Barbell,
+		Sparkle,
+	} from '@mana/shared-icons';
+
+	type Weight = 'thin' | 'light' | 'regular' | 'bold' | 'fill' | 'duotone';
+
+	interface Props {
+		category: DeckCategoryId;
+		size?: number;
+		color?: string | null;
+		weight?: Weight;
+	}
+
+	let { category, size = 32, color = null, weight = 'duotone' }: Props = $props();
+
+	const ICON_MAP: Record<DeckCategoryId, typeof Globe> = {
+		language: Globe,
+		medicine: Heartbeat,
+		science: Leaf,
+		math: Brain,
+		history: Flag,
+		law: Medal,
+		technology: Lightning,
+		arts: Palette,
+		music: MusicNote,
+		sport: Barbell,
+		other: Sparkle,
+	};
+
+	const IconComponent = $derived(ICON_MAP[category]);
+</script>
+
+{#if IconComponent}
+	<IconComponent {size} {weight} color={color ?? undefined} />
+{/if}
diff --git a/apps/web/src/lib/components/marketplace/DeckListGrid.svelte b/apps/web/src/lib/components/marketplace/DeckListGrid.svelte
index d488308..6c2f265 100644
--- a/apps/web/src/lib/components/marketplace/DeckListGrid.svelte
+++ b/apps/web/src/lib/components/marketplace/DeckListGrid.svelte
@@ -1,6 +1,9 @@
 <script lang="ts">
 	import type { DeckListEntry } from '$lib/api/marketplace.ts';
+	import type { DeckCategoryId } from '@cards/domain';
+	import { DECK_CATEGORY_IDS } from '@cards/domain';
 	import AuthorBadge from './AuthorBadge.svelte';
+	import DeckCategoryIcon from '$lib/components/DeckCategoryIcon.svelte';
 
 	interface Props {
 		items: DeckListEntry[];
@@ -9,6 +12,10 @@
 
 	const { items, emptyMessage = 'Noch keine Decks gefunden.' }: Props = $props();
 
+	function isValidCategory(c: string | null): c is DeckCategoryId {
+		return c !== null && (DECK_CATEGORY_IDS as readonly string[]).includes(c);
+	}
+
 	function languageLabel(code: string | null): string {
 		if (!code) return '';
 		const map: Record<string, string> = { de: 'Deutsch', en: 'English', es: 'Español', fr: 'Français' };
@@ -29,14 +36,21 @@
 				<a href="/d/{deck.slug}" class="block">
 					<div class="flex items-start justify-between gap-2">
 						<h3 class="truncate font-medium">{deck.title}</h3>
-						{#if deck.is_featured}
-							<span
-								class="shrink-0 rounded-full bg-[hsl(var(--color-primary))]/15 px-2 py-0.5 text-[10px] font-medium text-[hsl(var(--color-primary))]"
-								title="Editorial Pick"
-							>
-								★ Featured
-							</span>
-						{/if}
+						<div class="flex shrink-0 items-center gap-1.5">
+							{#if isValidCategory(deck.category)}
+								<span class="text-[hsl(var(--color-muted-foreground))]" aria-hidden="true">
+									<DeckCategoryIcon category={deck.category} size={16} weight="duotone" />
+								</span>
+							{/if}
+							{#if deck.is_featured}
+								<span
+									class="rounded-full bg-[hsl(var(--color-primary))]/15 px-2 py-0.5 text-[10px] font-medium text-[hsl(var(--color-primary))]"
+									title="Editorial Pick"
+								>
+									★ Featured
+								</span>
+							{/if}
+						</div>
 					</div>
 					{#if deck.description}
 						<p
diff --git a/apps/web/src/routes/+layout.svelte b/apps/web/src/routes/+layout.svelte
index 35e63dd..cc9bf0f 100644
--- a/apps/web/src/routes/+layout.svelte
+++ b/apps/web/src/routes/+layout.svelte
@@ -50,7 +50,7 @@
 
 	.default-pad {
 		max-width: 72rem;
-		padding: 2rem 1rem;
+		padding: 2rem 1rem 6rem;
 	}
 
 	/* Focus-Mode: keine max-width-Begrenzung, kein Außen-Padding —
diff --git a/apps/web/src/routes/decks/[id]/+page.svelte b/apps/web/src/routes/decks/[id]/+page.svelte
index 9d467ca..179d4b7 100644
--- a/apps/web/src/routes/decks/[id]/+page.svelte
+++ b/apps/web/src/routes/decks/[id]/+page.svelte
@@ -3,13 +3,15 @@
 	import { page } from '$app/state';
 	import { goto } from '$app/navigation';
 	import type { Card, Deck } from '@cards/domain';
-	import { getDeck } from '$lib/api/decks.ts';
+	import { type DeckCategoryId, DECK_CATEGORY_IDS, DECK_CATEGORY_LABELS } from '@cards/domain';
+	import { getDeck, updateDeck } from '$lib/api/decks.ts';
 	import { listCards, deleteCard } from '$lib/api/cards.ts';
 	import { listDueReviews } from '$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 '$lib/i18n/index.svelte.ts';
 	import DeckFan from '$lib/components/DeckFan.svelte';
+	import DeckCategoryIcon from '$lib/components/DeckCategoryIcon.svelte';
 
 	let deck = $state<Deck | null>(null);
 	let cards = $state<Card[]>([]);
@@ -46,6 +48,16 @@
 		}
 	}
 
+	async function onSetCategory(id: DeckCategoryId) {
+		if (!deck) return;
+		const next = deck.category === id ? null : id;
+		try {
+			deck = await updateDeck(deck.id, { category: next ?? undefined });
+		} catch (e) {
+			toasts.error((e as Error).message);
+		}
+	}
+
 	async function onDeleteCard(id: string) {
 		if (!confirm(t('deck_detail.card_delete_confirm'))) return;
 		try {
@@ -112,6 +124,24 @@
 		{tn('decks.card_count', cards.length)} · {t('study.due_count', { n: dueCount })}
 	</div>
 
+	<div class="category-row mt-3">
+		{#each DECK_CATEGORY_IDS as id}
+			<button
+				class="cat-btn"
+				class:active={deck.category === id}
+				onclick={() => onSetCategory(id)}
+			>
+				<DeckCategoryIcon
+					category={id}
+					size={16}
+					color={deck.category === id ? (deck.color ?? null) : null}
+					weight={deck.category === id ? 'fill' : 'regular'}
+				/>
+				<span class="cat-label">{DECK_CATEGORY_LABELS[id]}</span>
+			</button>
+		{/each}
+	</div>
+
 	{#if cards.length === 0}
 		<div
 			class="mt-8 rounded-lg border border-dashed border-[hsl(var(--color-border))] p-12 text-center"
@@ -183,6 +213,41 @@
 {/if}
 
 <style>
+	.category-row {
+		display: flex;
+		flex-wrap: wrap;
+		gap: 0.25rem;
+	}
+
+	.cat-btn {
+		display: inline-flex;
+		align-items: center;
+		gap: 0.3rem;
+		padding: 0.25rem 0.5rem;
+		border-radius: 0.375rem;
+		border: 1px solid transparent;
+		background: transparent;
+		color: hsl(var(--color-muted-foreground));
+		cursor: pointer;
+		transition: border-color 0.12s, background 0.12s, color 0.12s;
+	}
+
+	.cat-btn:hover {
+		border-color: hsl(var(--color-border));
+		color: hsl(var(--color-foreground));
+	}
+
+	.cat-btn.active {
+		border-color: hsl(var(--color-primary) / 0.4);
+		background: hsl(var(--color-primary) / 0.08);
+		color: hsl(var(--color-foreground));
+	}
+
+	.cat-label {
+		font-size: 0.75rem;
+		font-weight: 500;
+	}
+
 	.list-toggle {
 		cursor: pointer;
 		font-size: 0.875rem;
diff --git a/packages/cards-domain/src/schemas/deck.ts b/packages/cards-domain/src/schemas/deck.ts
index edf8e79..eb492ba 100644
--- a/packages/cards-domain/src/schemas/deck.ts
+++ b/packages/cards-domain/src/schemas/deck.ts
@@ -4,6 +4,37 @@ import { FsrsSettingsSchema } from './fsrs-settings.ts';
 
 const VisibilitySchema = z.enum(['private', 'space', 'public']);
 
+export const DECK_CATEGORY_IDS = [
+	'language',
+	'medicine',
+	'science',
+	'math',
+	'history',
+	'law',
+	'technology',
+	'arts',
+	'music',
+	'sport',
+	'other',
+] as const;
+
+export type DeckCategoryId = (typeof DECK_CATEGORY_IDS)[number];
+export const DeckCategorySchema = z.enum(DECK_CATEGORY_IDS);
+
+export const DECK_CATEGORY_LABELS: Record<DeckCategoryId, string> = {
+	language: 'Sprache',
+	medicine: 'Medizin',
+	science: 'Wissenschaft',
+	math: 'Mathematik',
+	history: 'Geschichte',
+	law: 'Recht',
+	technology: 'Technik',
+	arts: 'Kunst',
+	music: 'Musik',
+	sport: 'Sport',
+	other: 'Sonstiges',
+};
+
 export const DeckSchema = z
 	.object({
 		id: z.string().min(1),
@@ -15,6 +46,7 @@ export const DeckSchema = z
 			.regex(/^#[0-9a-fA-F]{6}$/)
 			.optional()
 			.nullable(),
+		category: DeckCategorySchema.optional().nullable(),
 		visibility: VisibilitySchema.default('private'),
 		fsrs_settings: FsrsSettingsSchema.default({}),
 		content_hash: z.string().optional().nullable(),
@@ -32,6 +64,7 @@ export const DeckCreateSchema = z
 			.string()
 			.regex(/^#[0-9a-fA-F]{6}$/)
 			.optional(),
+		category: DeckCategorySchema.optional(),
 		visibility: VisibilitySchema.optional(),
 		fsrs_settings: FsrsSettingsSchema.optional(),
 	})
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index 965334e..f382765 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -69,6 +69,9 @@ importers:
       '@cards/domain':
         specifier: workspace:*
         version: link:../../packages/cards-domain
+      '@mana/shared-icons':
+        specifier: ^1.0.0
+        version: 1.0.0(svelte@5.55.5)(vite@5.4.21(@types/node@22.19.18)(lightningcss@1.32.0))
       '@mana/shared-ui-2':
         specifier: ^0.1.0
         version: 0.1.0(svelte@5.55.5)
@@ -578,6 +581,11 @@ packages:
   '@jridgewell/trace-mapping@0.3.31':
     resolution: {integrity: sha512-zzNR+SdQSDJzc8joaeP8QQoCQr8NuYx2dIIytl1QeBEZHJ9uW6hebsrYgbz8hJwUQao3TWCMtmfV8Nu1twOLAw==}
 
+  '@mana/shared-icons@1.0.0':
+    resolution: {integrity: sha512-71L1dLO6tias8floLv8s0MYzv4cA5IvwftxdFnTYOsKMTMkJ2xEiJ4VxoV5Rj7iAG0oCdV5cmjGyOEKWaLVGEA==}
+    peerDependencies:
+      svelte: ^5.0.0
+
   '@mana/shared-share-protocol@0.1.0':
     resolution: {integrity: sha512-I1fIDbS3nu++9LUXc08ICrLXE/cdV/n9D0Jm8LOhVH9izUXQSSg2EO4M2+m7K5vc5KdjGBcYrFPhAg48+KE6Kw==}
     hasBin: true
@@ -1513,6 +1521,15 @@ packages:
     resolution: {integrity: sha512-//nshmD55c46FuFw26xV/xFAaB5HF9Xdap7HJBBnrKdAd6/GxDBaNA1870O79+9ueg61cZLSVc+OaFlfmObYVQ==}
     engines: {node: '>= 14.16'}
 
+  phosphor-svelte@3.1.0:
+    resolution: {integrity: sha512-nldtxx+XCgNREvrb7O5xgDsefytXpSkPTx8Rnu3f2qQCUZLDV1rLxYSd2Jcwckuo9lZB1qKMqGR17P4UDC0PrA==}
+    peerDependencies:
+      svelte: ^5.0.0 || ^5.0.0-next.96
+      vite: '>=5'
+    peerDependenciesMeta:
+      vite:
+        optional: true
+
   picocolors@1.1.1:
     resolution: {integrity: sha512-xceH2snhtb5M9liqDsmEw56le376mTZkEX/jEb/RxNFyegNul7eNslCXP9FDj/Lcu0X8KEyMceP2ntpaHrDEVA==}
 
@@ -2095,6 +2112,13 @@ snapshots:
       '@jridgewell/resolve-uri': 3.1.2
       '@jridgewell/sourcemap-codec': 1.5.5
 
+  '@mana/shared-icons@1.0.0(svelte@5.55.5)(vite@5.4.21(@types/node@22.19.18)(lightningcss@1.32.0))':
+    dependencies:
+      phosphor-svelte: 3.1.0(svelte@5.55.5)(vite@5.4.21(@types/node@22.19.18)(lightningcss@1.32.0))
+      svelte: 5.55.5
+    transitivePeerDependencies:
+      - vite
+
   '@mana/shared-share-protocol@0.1.0':
     dependencies:
       zod: 3.25.76
@@ -2861,6 +2885,14 @@ snapshots:
 
   pathval@2.0.1: {}
 
+  phosphor-svelte@3.1.0(svelte@5.55.5)(vite@5.4.21(@types/node@22.19.18)(lightningcss@1.32.0)):
+    dependencies:
+      estree-walker: 3.0.3
+      magic-string: 0.30.21
+      svelte: 5.55.5
+    optionalDependencies:
+      vite: 5.4.21(@types/node@22.19.18)(lightningcss@1.32.0)
+
   picocolors@1.1.1: {}
 
   picomatch@4.0.4: {}