diff --git a/app/api/internal.py b/app/api/internal.py
index 411f67e..e5e4f8b 100644
--- a/app/api/internal.py
+++ b/app/api/internal.py
@@ -1,4 +1,4 @@
-from fastapi import APIRouter, Depends, Header, HTTPException, status
+from fastapi import APIRouter, Depends, HTTPException, status
 from sqlalchemy.orm import Session
 
 from app.core.config import get_settings
@@ -8,24 +8,16 @@ from app.repositories.users_repo import UsersRepository
 from app.schemas.authentik_admin import AuthentikEnsureUserRequest, AuthentikEnsureUserResponse
 from app.schemas.permissions import PermissionSnapshotResponse
 from app.schemas.users import UserUpsertBySubRequest
+from app.security.api_client_auth import require_api_client
 from app.services.authentik_admin_service import AuthentikAdminService
 from app.services.permission_service import PermissionService
 
-router = APIRouter(prefix="/internal", tags=["internal"])
-
-
-def verify_internal_secret(x_internal_secret: str = Header(alias="X-Internal-Secret")) -> None:
-    settings = get_settings()
-    if not settings.internal_shared_secret:
-        raise HTTPException(status_code=status.HTTP_503_SERVICE_UNAVAILABLE, detail="internal_secret_not_configured")
-    if x_internal_secret != settings.internal_shared_secret:
-        raise HTTPException(status_code=status.HTTP_401_UNAUTHORIZED, detail="invalid_internal_secret")
+router = APIRouter(prefix="/internal", tags=["internal"], dependencies=[Depends(require_api_client)])
 
 
 @router.post("/users/upsert-by-sub")
 def upsert_user_by_sub(
     payload: UserUpsertBySubRequest,
-    _: None = Depends(verify_internal_secret),
     db: Session = Depends(get_db),
 ) -> dict[str, str | bool | None]:
     repo = UsersRepository(db)
@@ -50,7 +42,6 @@ def upsert_user_by_sub(
 @router.get("/permissions/{authentik_sub}/snapshot", response_model=PermissionSnapshotResponse)
 def get_permission_snapshot(
     authentik_sub: str,
-    _: None = Depends(verify_internal_secret),
     db: Session = Depends(get_db),
 ) -> PermissionSnapshotResponse:
     users_repo = UsersRepository(db)
@@ -67,7 +58,6 @@ def get_permission_snapshot(
 @router.post("/authentik/users/ensure", response_model=AuthentikEnsureUserResponse)
 def ensure_authentik_user(
     payload: AuthentikEnsureUserRequest,
-    _: None = Depends(verify_internal_secret),
     db: Session = Depends(get_db),
 ) -> AuthentikEnsureUserResponse:
     settings = get_settings()
diff --git a/app/api/internal_catalog.py b/app/api/internal_catalog.py
index 6c05269..abf4ad4 100644
--- a/app/api/internal_catalog.py
+++ b/app/api/internal_catalog.py
@@ -1,20 +1,19 @@
 from fastapi import APIRouter, Depends, Query
 from sqlalchemy.orm import Session
 
-from app.api.internal import verify_internal_secret
 from app.db.session import get_db
 from app.repositories.companies_repo import CompaniesRepository
 from app.repositories.modules_repo import ModulesRepository
 from app.repositories.sites_repo import SitesRepository
 from app.repositories.systems_repo import SystemsRepository
 from app.repositories.users_repo import UsersRepository
+from app.security.api_client_auth import require_api_client
 
-router = APIRouter(prefix="/internal", tags=["internal"])
+router = APIRouter(prefix="/internal", tags=["internal"], dependencies=[Depends(require_api_client)])
 
 
 @router.get("/systems")
 def internal_list_systems(
-    _: None = Depends(verify_internal_secret),
     db: Session = Depends(get_db),
     limit: int = Query(default=200, ge=1, le=1000),
     offset: int = Query(default=0, ge=0),
@@ -26,7 +25,6 @@ def internal_list_systems(
 
 @router.get("/modules")
 def internal_list_modules(
-    _: None = Depends(verify_internal_secret),
     db: Session = Depends(get_db),
     limit: int = Query(default=500, ge=1, le=2000),
     offset: int = Query(default=0, ge=0),
@@ -52,7 +50,6 @@ def internal_list_modules(
 
 @router.get("/companies")
 def internal_list_companies(
-    _: None = Depends(verify_internal_secret),
     db: Session = Depends(get_db),
     keyword: str | None = Query(default=None),
     limit: int = Query(default=500, ge=1, le=2000),
@@ -65,7 +62,6 @@ def internal_list_companies(
 
 @router.get("/sites")
 def internal_list_sites(
-    _: None = Depends(verify_internal_secret),
     db: Session = Depends(get_db),
     company_key: str | None = Query(default=None),
     limit: int = Query(default=500, ge=1, le=2000),
@@ -86,7 +82,6 @@ def internal_list_sites(
 
 @router.get("/members")
 def internal_list_members(
-    _: None = Depends(verify_internal_secret),
     db: Session = Depends(get_db),
     keyword: str | None = Query(default=None),
     limit: int = Query(default=500, ge=1, le=2000),
diff --git a/tests/test_internal_authentik_sync.py b/tests/test_internal_authentik_sync.py
index 8ea80a7..a48d522 100644
--- a/tests/test_internal_authentik_sync.py
+++ b/tests/test_internal_authentik_sync.py
@@ -1,19 +1,23 @@
 from fastapi.testclient import TestClient
 
 from app.main import app
+from app.security.api_client_auth import require_api_client
 
 
 def test_internal_authentik_ensure_requires_config() -> None:
+    app.dependency_overrides[require_api_client] = lambda: None
     client = TestClient(app)
-    resp = client.post(
-        "/internal/authentik/users/ensure",
-        headers={"X-Internal-Secret": "CHANGE_ME"},
-        json={
-            "sub": "authentik-sub-1",
-            "email": "user@example.com",
-            "display_name": "User Example",
-            "is_active": True,
-        },
-    )
-    assert resp.status_code == 503
-    assert resp.json()["detail"] == "authentik_admin_not_configured"
+    try:
+        resp = client.post(
+            "/internal/authentik/users/ensure",
+            json={
+                "sub": "authentik-sub-1",
+                "email": "user@example.com",
+                "display_name": "User Example",
+                "is_active": True,
+            },
+        )
+        assert resp.status_code == 503
+        assert resp.json()["detail"] == "authentik_admin_not_configured"
+    finally:
+        app.dependency_overrides.pop(require_api_client, None)