diff --git a/src/database/setups.py b/src/database/setups.py
new file mode 100644
index 00000000..59601ae4
--- /dev/null
+++ b/src/database/setups.py
@@ -0,0 +1,42 @@
+from sqlalchemy import Connection, text
+from sqlalchemy.engine import Row
+
+
+def get(setup_id: int, connection: Connection) -> Row | None:
+    row = connection.execute(
+        text(
+            """
+            SELECT *
+            FROM algorithm_setup
+            WHERE sid = :setup_id
+            """,
+        ),
+        parameters={"setup_id": setup_id},
+    )
+    return row.first()
+
+
+def get_tags(setup_id: int, connection: Connection) -> list[Row]:
+    rows = connection.execute(
+        text(
+            """
+            SELECT *
+            FROM setup_tag
+            WHERE id = :setup_id
+            """,
+        ),
+        parameters={"setup_id": setup_id},
+    )
+    return list(rows.all())
+
+
+def untag(setup_id: int, tag: str, connection: Connection) -> None:
+    connection.execute(
+        text(
+            """
+            DELETE FROM setup_tag
+            WHERE id = :setup_id AND tag = :tag
+            """,
+        ),
+        parameters={"setup_id": setup_id, "tag": tag},
+    )
diff --git a/src/main.py b/src/main.py
index 560b4c50..07e14510 100644
--- a/src/main.py
+++ b/src/main.py
@@ -11,6 +11,7 @@
 from routers.openml.evaluations import router as evaluationmeasures_router
 from routers.openml.flows import router as flows_router
 from routers.openml.qualities import router as qualities_router
+from routers.openml.setups import router as setup_router
 from routers.openml.study import router as study_router
 from routers.openml.tasks import router as task_router
 from routers.openml.tasktype import router as ttype_router
@@ -55,6 +56,7 @@ def create_api() -> FastAPI:
     app.include_router(task_router)
     app.include_router(flows_router)
     app.include_router(study_router)
+    app.include_router(setup_router)
     return app
 
 
diff --git a/src/routers/dependencies.py b/src/routers/dependencies.py
index 2ddccf83..e4de107f 100644
--- a/src/routers/dependencies.py
+++ b/src/routers/dependencies.py
@@ -1,6 +1,7 @@
+from http import HTTPStatus
 from typing import Annotated
 
-from fastapi import Depends
+from fastapi import Depends, HTTPException
 from pydantic import BaseModel
 from sqlalchemy import Connection
 
@@ -29,6 +30,17 @@ def fetch_user(
     return User.fetch(api_key, user_data) if api_key else None
 
 
+def fetch_user_or_raise(
+    user: Annotated[User | None, Depends(fetch_user)] = None,
+) -> User:
+    if user is None:
+        raise HTTPException(
+            status_code=HTTPStatus.PRECONDITION_FAILED,
+            detail={"code": "103", "message": "Authentication failed"},
+        )
+    return user
+
+
 class Pagination(BaseModel):
     offset: int = 0
     limit: int = 100
diff --git a/src/routers/openml/datasets.py b/src/routers/openml/datasets.py
index dda25117..2bc1548d 100644
--- a/src/routers/openml/datasets.py
+++ b/src/routers/openml/datasets.py
@@ -19,7 +19,13 @@
     _format_parquet_url,
 )
 from database.users import User, UserGroup
-from routers.dependencies import Pagination, expdb_connection, fetch_user, userdb_connection
+from routers.dependencies import (
+    Pagination,
+    expdb_connection,
+    fetch_user,
+    fetch_user_or_raise,
+    userdb_connection,
+)
 from routers.types import CasualString128, IntegerRange, SystemString64, integer_range_regex
 from schemas.datasets.openml import DatasetMetadata, DatasetStatus, Feature, FeatureType
 
@@ -32,29 +38,19 @@
 def tag_dataset(
     data_id: Annotated[int, Body()],
     tag: Annotated[str, SystemString64],
-    user: Annotated[User | None, Depends(fetch_user)] = None,
+    user: Annotated[User, Depends(fetch_user_or_raise)],
     expdb_db: Annotated[Connection, Depends(expdb_connection)] = None,
 ) -> dict[str, dict[str, Any]]:
     tags = database.datasets.get_tags_for(data_id, expdb_db)
     if tag.casefold() in [t.casefold() for t in tags]:
         raise create_tag_exists_error(data_id, tag)
 
-    if user is None:
-        raise create_authentication_failed_error()
-
     database.datasets.tag(data_id, tag, user_id=user.user_id, connection=expdb_db)
     return {
         "data_tag": {"id": str(data_id), "tag": [*tags, tag]},
     }
 
 
-def create_authentication_failed_error() -> HTTPException:
-    return HTTPException(
-        status_code=HTTPStatus.PRECONDITION_FAILED,
-        detail={"code": "103", "message": "Authentication failed"},
-    )
-
-
 def create_tag_exists_error(data_id: int, tag: str) -> HTTPException:
     return HTTPException(
         status_code=HTTPStatus.INTERNAL_SERVER_ERROR,
diff --git a/src/routers/openml/setups.py b/src/routers/openml/setups.py
new file mode 100644
index 00000000..71304e38
--- /dev/null
+++ b/src/routers/openml/setups.py
@@ -0,0 +1,45 @@
+from http import HTTPStatus
+from typing import Annotated
+
+from fastapi import APIRouter, Body, Depends, HTTPException
+from sqlalchemy import Connection
+
+import database.setups
+from database.users import User, UserGroup
+from routers.dependencies import expdb_connection, fetch_user_or_raise
+from routers.types import SystemString64
+
+router = APIRouter(prefix="/setup", tags=["setup"])
+
+
+@router.post(path="/untag")
+def untag_setup(
+    setup_id: Annotated[int, Body()],
+    tag: Annotated[str, SystemString64],
+    user: Annotated[User, Depends(fetch_user_or_raise)],
+    expdb_db: Annotated[Connection, Depends(expdb_connection)] = None,
+) -> dict[str, dict[str, str]]:
+    if not database.setups.get(setup_id, expdb_db):
+        raise HTTPException(
+            status_code=HTTPStatus.PRECONDITION_FAILED,
+            detail={"code": "472", "message": "Entity not found."},
+        )
+
+    setup_tags = database.setups.get_tags(setup_id, expdb_db)
+    matched_tag_row = next((t for t in setup_tags if t.tag.casefold() == tag.casefold()), None)
+
+    if not matched_tag_row:
+        raise HTTPException(
+            status_code=HTTPStatus.PRECONDITION_FAILED,
+            detail={"code": "475", "message": "Tag not found."},
+        )
+
+    if matched_tag_row.uploader != user.user_id and UserGroup.ADMIN not in user.groups:
+        raise HTTPException(
+            status_code=HTTPStatus.PRECONDITION_FAILED,
+            detail={"code": "476", "message": "Tag is not owned by you"},
+        )
+
+    database.setups.untag(setup_id, matched_tag_row.tag, expdb_db)
+
+    return {"setup_untag": {"id": str(setup_id)}}
diff --git a/tests/routers/openml/migration/setups_migration_test.py b/tests/routers/openml/migration/setups_migration_test.py
new file mode 100644
index 00000000..a744dc39
--- /dev/null
+++ b/tests/routers/openml/migration/setups_migration_test.py
@@ -0,0 +1,62 @@
+from http import HTTPStatus
+
+import httpx
+import pytest
+from starlette.testclient import TestClient
+
+from tests.users import ApiKey
+
+
+@pytest.mark.parametrize(
+    "setup_id",
+    [1, 999999],
+    ids=["existing setup", "unknown setup"],
+)
+@pytest.mark.parametrize(
+    "api_key",
+    [ApiKey.ADMIN, ApiKey.SOME_USER, ApiKey.OWNER_USER],
+    ids=["Administrator", "regular user", "possible owner"],
+)
+@pytest.mark.parametrize(
+    "tag",
+    ["totally_new_tag_for_migration_testing"],
+)
+def test_setup_untag_response_is_identical(
+    setup_id: int,
+    tag: str,
+    api_key: str,
+    py_api: TestClient,
+    php_api: httpx.Client,
+) -> None:
+    if setup_id == 1:
+        php_api.post(
+            "/setup/tag",
+            data={"api_key": ApiKey.SOME_USER, "tag": tag, "setup_id": setup_id},
+        )
+
+    original = php_api.post(
+        "/setup/untag",
+        data={"api_key": api_key, "tag": tag, "setup_id": setup_id},
+    )
+
+    if original.status_code == HTTPStatus.OK:
+        php_api.post(
+            "/setup/tag",
+            data={"api_key": ApiKey.SOME_USER, "tag": tag, "setup_id": setup_id},
+        )
+
+    new = py_api.post(
+        f"/setup/untag?api_key={api_key}",
+        json={"setup_id": setup_id, "tag": tag},
+    )
+
+    assert original.status_code == new.status_code
+
+    if new.status_code != HTTPStatus.OK:
+        assert original.json()["error"] == new.json()["detail"]
+        return
+
+    original_json = original.json()
+    new_json = new.json()
+
+    assert original_json == new_json
diff --git a/tests/routers/openml/setups_test.py b/tests/routers/openml/setups_test.py
new file mode 100644
index 00000000..50b6b843
--- /dev/null
+++ b/tests/routers/openml/setups_test.py
@@ -0,0 +1,88 @@
+from collections.abc import Iterator
+from http import HTTPStatus
+
+import pytest
+from sqlalchemy import Connection, text
+from starlette.testclient import TestClient
+
+from tests.users import ApiKey
+
+
+@pytest.fixture
+def mock_setup_tag(expdb_test: Connection) -> Iterator[None]:
+    expdb_test.execute(
+        text("DELETE FROM setup_tag WHERE id = 1 AND tag = 'test_unit_tag_123'"),
+    )
+    expdb_test.execute(
+        text("INSERT INTO setup_tag (id, tag, uploader) VALUES (1, 'test_unit_tag_123', 2)")
+    )
+    expdb_test.commit()
+
+    yield
+
+    expdb_test.execute(
+        text("DELETE FROM setup_tag WHERE id = 1 AND tag = 'test_unit_tag_123'"),
+    )
+    expdb_test.commit()
+
+
+def test_setup_untag_missing_auth(py_api: TestClient) -> None:
+    response = py_api.post("/setup/untag", json={"setup_id": 1, "tag": "test_tag"})
+    assert response.status_code == HTTPStatus.PRECONDITION_FAILED
+    assert response.json()["detail"] == {"code": "103", "message": "Authentication failed"}
+
+
+def test_setup_untag_unknown_setup(py_api: TestClient) -> None:
+    response = py_api.post(
+        f"/setup/untag?api_key={ApiKey.SOME_USER}",
+        json={"setup_id": 999999, "tag": "test_tag"},
+    )
+    assert response.status_code == HTTPStatus.PRECONDITION_FAILED
+    assert response.json()["detail"] == {"code": "472", "message": "Entity not found."}
+
+
+def test_setup_untag_tag_not_found(py_api: TestClient) -> None:
+    response = py_api.post(
+        f"/setup/untag?api_key={ApiKey.SOME_USER}",
+        json={"setup_id": 1, "tag": "non_existent_tag_12345"},
+    )
+    assert response.status_code == HTTPStatus.PRECONDITION_FAILED
+    assert response.json()["detail"] == {"code": "475", "message": "Tag not found."}
+
+
+@pytest.mark.mut
+@pytest.mark.usefixtures("mock_setup_tag")
+def test_setup_untag_not_owned_by_you(py_api: TestClient) -> None:
+    response = py_api.post(
+        f"/setup/untag?api_key={ApiKey.OWNER_USER}",
+        json={"setup_id": 1, "tag": "test_unit_tag_123"},
+    )
+    assert response.status_code == HTTPStatus.PRECONDITION_FAILED
+    assert response.json()["detail"] == {"code": "476", "message": "Tag is not owned by you"}
+
+
+@pytest.mark.mut
+@pytest.mark.parametrize(
+    "api_key",
+    [ApiKey.SOME_USER, ApiKey.ADMIN],
+    ids=["Owner", "Administrator"],
+)
+def test_setup_untag_success(api_key: str, py_api: TestClient, expdb_test: Connection) -> None:
+    expdb_test.execute(text("DELETE FROM setup_tag WHERE id = 1 AND tag = 'test_success_tag'"))
+    expdb_test.execute(
+        text("INSERT INTO setup_tag (id, tag, uploader) VALUES (1, 'test_success_tag', 2)")
+    )
+    expdb_test.commit()
+
+    response = py_api.post(
+        f"/setup/untag?api_key={api_key}",
+        json={"setup_id": 1, "tag": "test_success_tag"},
+    )
+
+    assert response.status_code == HTTPStatus.OK
+    assert response.json() == {"setup_untag": {"id": "1"}}
+
+    rows = expdb_test.execute(
+        text("SELECT * FROM setup_tag WHERE id = 1 AND tag = 'test_success_tag'")
+    ).all()
+    assert len(rows) == 0