diff --git a/backend/open_webui/main.py b/backend/open_webui/main.py
index e05497c6165c..037dec17377b 100644
--- a/backend/open_webui/main.py
+++ b/backend/open_webui/main.py
@@ -509,6 +509,10 @@
     users,
     utils,
 )
+
+# AarhusAI patch: data pruning endpoint
+from open_webui.routers import aak_prune
+
 from open_webui.routers.retrieval import (
     get_ef,
     get_embedding_function,
@@ -1447,6 +1451,9 @@ async def lifespan(app: FastAPI):
 if ENABLE_ADMIN_ANALYTICS:
     app.include_router(analytics.router, prefix='/api/v1/analytics', tags=['analytics'])
 app.include_router(utils.router, prefix='/api/v1/utils', tags=['utils'])
+
+# AarhusAI patch: data pruning endpoint
+app.include_router(aak_prune.router, prefix='/api/v1/prune', tags=['prune'])
 app.include_router(terminals.router, prefix='/api/v1/terminals', tags=['terminals'])
 app.include_router(automations.router, prefix='/api/v1/automations', tags=['automations'])
 app.include_router(calendar.router, prefix='/api/v1/calendars', tags=['calendars'])
diff --git a/backend/open_webui/routers/aak_prune.py b/backend/open_webui/routers/aak_prune.py
new file mode 100644
index 000000000000..843a841aae3c
--- /dev/null
+++ b/backend/open_webui/routers/aak_prune.py
@@ -0,0 +1,96 @@
+# patch (AAK): data-pruning endpoint for the ITK AI Platform (Aarhus Kommune).
+#
+# Upstream open-webui has no data-retention mechanism, so chats accumulate
+# indefinitely. This router adds an admin-only endpoint that deletes chats
+# not updated for a given number of days, intended to be called from a cron
+# job. The endpoint lives in its own file so the patch only touches main.py
+# for import and registration.
+
+from __future__ import annotations
+
+import logging
+import time
+from typing import Optional
+
+from fastapi import APIRouter, Depends, Query
+from open_webui.internal.db import get_async_session
+from open_webui.models.chats import Chat, Chats
+from open_webui.utils.auth import get_admin_user
+from pydantic import BaseModel
+from sqlalchemy import select
+from sqlalchemy.ext.asyncio import AsyncSession
+
+log = logging.getLogger(__name__)
+
+router = APIRouter()
+
+
+class PruneChatsResponse(BaseModel):
+    dry_run: bool
+    days: int
+    cutoff: int
+    matched: int
+    deleted: int
+    failed: int
+
+
+@router.post('/chats', response_model=PruneChatsResponse)
+async def prune_chats(
+    days: int = Query(..., ge=1, description='Delete chats not updated for this many days'),
+    dry_run: bool = Query(False, description='Only report what would be deleted'),
+    limit: Optional[int] = Query(None, ge=1, description='Cap the number of chats deleted in this call'),
+    user=Depends(get_admin_user),
+    db: AsyncSession = Depends(get_async_session),
+):
+    # Chats last updated before this epoch timestamp are pruned.
+    cutoff = int(time.time()) - days * 24 * 60 * 60
+
+    # Pinned chats are deliberately spared; archived chats are pruned by age
+    # like any other. Oldest first, so a limited run works through the backlog.
+    query = (
+        select(Chat.id, Chat.user_id, Chat.meta)
+        .where(Chat.updated_at < cutoff)
+        .where(Chat.pinned.isnot(True))
+        .order_by(Chat.updated_at.asc())
+    )
+    if limit is not None:
+        query = query.limit(limit)
+
+    rows = (await db.execute(query)).all()
+
+    matched = len(rows)
+    deleted = 0
+    failed = 0
+
+    if not dry_run:
+        # Track which tags (meta['tags']) the deleted chats used, per user,
+        # so tags no longer used by any chat can be removed afterwards.
+        tag_ids_by_user: dict[str, set[str]] = {}
+        for row in rows:
+            # One transaction per chat: a failure mid-run leaves already
+            # deleted chats gone and reports the rest as failed.
+            if await Chats.delete_chat_by_id(row.id):
+                deleted += 1
+                tag_ids_by_user.setdefault(row.user_id, set()).update((row.meta or {}).get('tags', []))
+            else:
+                failed += 1
+
+        for user_id, tag_ids in tag_ids_by_user.items():
+            if tag_ids:
+                # We already deleted the chats, so an orphaned tag has zero
+                # remaining references, so we use threshold=0.
+                await Chats.delete_orphan_tags_for_user(list(tag_ids), user_id, threshold=0, db=db)
+
+        log.info(
+            f'prune_chats by {user.email}: days={days} cutoff={cutoff} '
+            f'matched={matched} deleted={deleted} failed={failed}'
+        )
+
+    return PruneChatsResponse(
+        dry_run=dry_run,
+        days=days,
+        cutoff=cutoff,
+        matched=matched,
+        deleted=deleted,
+        failed=failed,
+    )