diff --git a/.env.example b/.env.example
index dd79e8a..3d5766b 100644
--- a/.env.example
+++ b/.env.example
@@ -65,6 +65,8 @@ OPENAI_MODEL=gpt-5-mini
 # Nur für Reasoning-Modelle (gpt-5*, o*): minimal|low|medium|high. Für andere Modelle leer lassen.
 OPENAI_REASONING_EFFORT=low
 OPENAI_TIMEOUT=90
+# Optional: OpenAI-kompatibler Endpunkt/Proxy, leer = api.openai.com
+OPENAI_BASE_URL=
 # Optionale Kostenbremse: KI-Aufrufe pro Tag (0 = unbegrenzt)
 AI_RATE_LIMIT_PER_USER_PER_DAY=0
 AI_RATE_LIMIT_GLOBAL_PER_DAY=0
diff --git a/README.md b/README.md
index 682a5d3..ef0f405 100644
--- a/README.md
+++ b/README.md
@@ -110,6 +110,7 @@ Alle Variablen stehen kommentiert in [`.env.example`](.env.example). Die wichtig
 | `ADMIN_EMAIL` / `ADMIN_PASSWORD` | Erster Admin (nur beim ersten Start) | leer |
 | `OPENAI_API_KEY` | Schaltet die KI-Funktionen frei | leer = KI aus |
 | `OPENAI_MODEL` | Modell für Text und Bilder (muss Vision + Structured Outputs können) | `gpt-5-mini` |
+| `OPENAI_BASE_URL` | Optional: OpenAI-kompatibler Endpunkt oder Proxy | leer |
 | `OPENAI_REASONING_EFFORT` | Für Reasoning-Modelle; bei anderen Modellen leer lassen | `low` |
 | `AI_RATE_LIMIT_PER_USER_PER_DAY` | KI-Aufrufe pro Nutzer/Tag, `0` = unbegrenzt | `0` |
 | `AI_RATE_LIMIT_GLOBAL_PER_DAY` | KI-Aufrufe gesamt/Tag, `0` = unbegrenzt | `0` |
diff --git a/config/settings.py b/config/settings.py
index 80ea0e4..7879801 100644
--- a/config/settings.py
+++ b/config/settings.py
@@ -149,6 +149,8 @@ OPENAI_MODEL = env("OPENAI_MODEL", "gpt-5-mini")
 # For reasoning models (gpt-5*, o*): minimal|low|medium|high. Leave empty for other models.
 OPENAI_REASONING_EFFORT = env("OPENAI_REASONING_EFFORT", "low")
 OPENAI_TIMEOUT = env_int("OPENAI_TIMEOUT", 90)
+# Optional: OpenAI-compatible endpoint or proxy (default: api.openai.com)
+OPENAI_BASE_URL = env("OPENAI_BASE_URL")
 # 0 = unlimited (default). Counted per call, including failed ones.
 AI_RATE_LIMIT_PER_USER_PER_DAY = env_int("AI_RATE_LIMIT_PER_USER_PER_DAY", 0)
 AI_RATE_LIMIT_GLOBAL_PER_DAY = env_int("AI_RATE_LIMIT_GLOBAL_PER_DAY", 0)
diff --git a/config/settings_test.py b/config/settings_test.py
index 3f3af35..1590b52 100644
--- a/config/settings_test.py
+++ b/config/settings_test.py
@@ -22,6 +22,7 @@ import ipaddress  # noqa: E402
 OPENAI_API_KEY = ""
 OPENAI_MODEL = "gpt-5-mini"
 OPENAI_REASONING_EFFORT = "low"
+OPENAI_BASE_URL = ""
 AI_RATE_LIMIT_PER_USER_PER_DAY = 0
 AI_RATE_LIMIT_GLOBAL_PER_DAY = 0
 COMMENT_RATE_LIMIT_PER_HOUR = 30
diff --git a/recipes/ai.py b/recipes/ai.py
index 382e3ae..e0fbb15 100644
--- a/recipes/ai.py
+++ b/recipes/ai.py
@@ -206,7 +206,8 @@ def _check_limits(user):
 
 
 def _client():
-    return openai.OpenAI(api_key=settings.OPENAI_API_KEY, timeout=settings.OPENAI_TIMEOUT, max_retries=1)
+    return openai.OpenAI(api_key=settings.OPENAI_API_KEY, timeout=settings.OPENAI_TIMEOUT, max_retries=1,
+                         base_url=settings.OPENAI_BASE_URL or None)
 
 
 def _create_completion(messages):
diff --git a/tests/test_ai.py b/tests/test_ai.py
index f91d26c..85c0fdb 100644
--- a/tests/test_ai.py
+++ b/tests/test_ai.py
@@ -313,3 +313,79 @@ def test_refusal_and_truncation(monkeypatch):
     monkeypatch.setattr(ai, "_client", lambda: StubClient(content='{"is_re', finish_reason="length"))
     with pytest.raises(ai.AIError, match="zu lang"):
         ai._create_completion([])
+
+
+# --- End to end through the real OpenAI SDK against a local stub server --------------------
+
+
+@pytest.fixture
+def stub_openai_server(settings):
+    """A local HTTP server that speaks enough of the Chat Completions API for one request."""
+    import threading
+    from http.server import BaseHTTPRequestHandler, HTTPServer
+
+    received = {}
+    reply = {"status": 200, "body": None}
+
+    class Handler(BaseHTTPRequestHandler):
+        def do_POST(self):
+            length = int(self.headers.get("Content-Length", 0))
+            received["path"] = self.path
+            received["auth"] = self.headers.get("Authorization")
+            received["body"] = json.loads(self.rfile.read(length))
+            body = reply["body"] or {
+                "id": "chatcmpl-test", "object": "chat.completion", "created": 0, "model": received["body"]["model"],
+                "choices": [{"index": 0, "finish_reason": "stop",
+                             "message": {"role": "assistant", "content": ai_answer(), "refusal": None}}],
+                "usage": {"prompt_tokens": 1, "completion_tokens": 1, "total_tokens": 2},
+            }
+            data = json.dumps(body).encode()
+            self.send_response(reply["status"])
+            self.send_header("Content-Type", "application/json")
+            self.send_header("Content-Length", str(len(data)))
+            self.end_headers()
+            self.wfile.write(data)
+
+        def log_message(self, *args):
+            pass
+
+    server = HTTPServer(("127.0.0.1", 0), Handler)
+    threading.Thread(target=server.serve_forever, daemon=True).start()
+    settings.OPENAI_API_KEY = "sk-test-local"
+    settings.OPENAI_BASE_URL = f"http://127.0.0.1:{server.server_port}/v1"
+    settings.OPENAI_MODEL = "stub-model"
+    yield received, reply
+    server.shutdown()
+
+
+@pytest.mark.django_db
+def test_end_to_end_ai_cleanup_through_sdk(stub_openai_server, user_client):
+    received, _ = stub_openai_server
+    response = user_client.post(reverse("recipes:create"), form_data(ai="1"))
+    assert response.status_code == 200
+    assert response.context["form"].initial["title"] == "Linsen-Dal"
+    assert received["path"] == "/v1/chat/completions"
+    assert received["auth"] == "Bearer sk-test-local"
+    body = received["body"]
+    assert body["model"] == "stub-model"
+    assert body["response_format"]["json_schema"]["strict"] is True
+    assert body["messages"][0]["role"] == "system"
+    assert not Recipe.objects.exists()
+
+
+@pytest.mark.django_db
+def test_end_to_end_api_error_through_sdk(stub_openai_server, user_client):
+    _, reply = stub_openai_server
+    reply["status"] = 401
+    reply["body"] = {"error": {"message": "Incorrect API key", "type": "invalid_request_error", "code": "invalid_api_key"}}
+    response = user_client.post(reverse("recipes:create"), form_data(ai="1"))
+    assert "API-Key ist ungültig" in response.content.decode()
+
+
+@pytest.mark.django_db
+def test_end_to_end_photo_import_through_sdk(stub_openai_server, user_client):
+    received, _ = stub_openai_server
+    response = user_client.post(reverse("recipes:import_photo"), {"photos": [image_upload()]})
+    assert response.context["form"].initial["title"] == "Linsen-Dal"
+    parts = received["body"]["messages"][1]["content"]
+    assert any(p["type"] == "image_url" and p["image_url"]["url"].startswith("data:image/jpeg;base64,") for p in parts)