diff --git a/databusclient/api/utils.py b/databusclient/api/utils.py
index df4f49d..ba6dfe5 100644
--- a/databusclient/api/utils.py
+++ b/databusclient/api/utils.py
@@ -28,12 +28,7 @@ def get_databus_id_parts_from_file_url(
         A tuple containing (host, accountId, groupId, artifactId, versionId, fileId).
         Each element is a string or None if not present.
     """
-    """Split a Databus URI into its six parts.
-
-    The returned tuple is (host, accountId, groupId, artifactId, versionId, fileId).
-    Missing parts are returned as ``None``.
-    """
-
+    
     uri = uri.removeprefix("https://").removeprefix("http://")
     parts = uri.strip("/").split("/")
     parts += [None] * (6 - len(parts))  # pad with None if less than 6 parts
diff --git a/tests/test_api_utils.py b/tests/test_api_utils.py
new file mode 100644
index 0000000..fe9ec05
--- /dev/null
+++ b/tests/test_api_utils.py
@@ -0,0 +1,175 @@
+import pytest
+import requests
+from databusclient.api import utils
+from databusclient.api.utils import (
+    get_databus_id_parts_from_file_url,
+    compute_sha256_and_length,
+    fetch_databus_jsonld,
+)
+
+
+def test_split_full_url():
+    result = get_databus_id_parts_from_file_url(
+        "https://databus.dbpedia.org/dbpedia/mappings/geo-coordinates/2022.12.01/file.ttl"
+    )
+    assert result == (
+        "databus.dbpedia.org",
+        "dbpedia",
+        "mappings",
+        "geo-coordinates",
+        "2022.12.01",
+        "file.ttl",
+    )
+
+
+def test_split_short_url_fills_none():
+    result = get_databus_id_parts_from_file_url(
+        "https://databus.dbpedia.org/dbpedia/mappings"
+    )
+    assert result == (
+        "databus.dbpedia.org",
+        "dbpedia",
+        "mappings",
+        None,
+        None,
+        None,
+    )
+
+
+def test_split_http_same_as_https():
+    result = get_databus_id_parts_from_file_url(
+        "http://databus.dbpedia.org/dbpedia/mappings/geo-coordinates/2022.12.01/file.ttl"
+    )
+    assert result == (
+        "databus.dbpedia.org",
+        "dbpedia",
+        "mappings",
+        "geo-coordinates",
+        "2022.12.01",
+        "file.ttl",
+    )
+
+
+def test_split_trailing_slash_ignored():
+    result = get_databus_id_parts_from_file_url(
+        "https://databus.dbpedia.org/dbpedia/mappings/geo-coordinates/2022.12.01/file.ttl/"
+    )
+    assert result == (
+        "databus.dbpedia.org",
+        "dbpedia",
+        "mappings",
+        "geo-coordinates",
+        "2022.12.01",
+        "file.ttl",
+    )
+
+
+def test_split_empty_string():
+    result = get_databus_id_parts_from_file_url("")
+    assert result == (
+        "",
+        None,
+        None,
+        None,
+        None,
+        None,
+    )
+
+
+def test_split_too_long_keeps_first_six():
+    result = get_databus_id_parts_from_file_url(
+        "https://databus.dbpedia.org/a/b/c/d/e/f/g/h"
+    )
+    assert result == (
+        "databus.dbpedia.org",
+        "a",
+        "b",
+        "c",
+        "d",
+        "e",
+    )
+
+
+def test_sha256_hello_file(tmp_path):
+    f = tmp_path / "hello.txt"
+    f.write_text("hello")
+    result = compute_sha256_and_length(f)
+
+    assert result == (
+        "2cf24dba5fb0a30e26e83b2ac5b9e29e1b161e5c1fa7425e73043362938b9824",
+        5,
+    )
+
+
+def test_sha256_empty_file(tmp_path):
+    f = tmp_path / "empty.txt"
+    f.write_text("")
+    result = compute_sha256_and_length(f)
+
+    assert result == (
+        "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855",
+        0,
+    )
+
+
+def test_sha256_missing_file_raises(tmp_path):
+    missing = tmp_path / "does_not_exist.txt"
+    with pytest.raises(FileNotFoundError):
+        compute_sha256_and_length(missing)
+
+
+class FakeResponse:
+    def __init__(self, text="", ok=True):
+        self.text = text
+        self.ok = ok
+
+    def raise_for_status(self):
+        if not self.ok:
+            raise requests.HTTPError("404 Not Found")
+
+
+def test_fetch_sends_accept_header_without_key(monkeypatch):
+    calls = {}
+
+    def fake_get(uri, headers, timeout):
+        calls["uri"] = uri
+        calls["headers"] = headers
+        return FakeResponse(text='{"ok": true}')
+
+    monkeypatch.setattr(utils.requests, "get", fake_get)
+
+    result = fetch_databus_jsonld("https://databus.dbpedia.org/dbpedia/mappings")
+
+    assert result == '{"ok": true}'
+    assert calls["headers"] == {"Accept": "application/ld+json"}
+
+
+def test_fetch_adds_api_key_header(monkeypatch):
+    calls = {}
+
+    def fake_get(uri, headers, timeout):
+        calls["uri"] = uri
+        calls["headers"] = headers
+        return FakeResponse(text='{"ok": true}')
+
+    monkeypatch.setattr(utils.requests, "get", fake_get)
+
+    result = fetch_databus_jsonld(
+        "https://databus.dbpedia.org/dbpedia/mappings", databus_key="secret123"
+    )
+
+    assert result == '{"ok": true}'
+    assert calls["headers"] == {
+        "Accept": "application/ld+json",
+        "X-API-KEY": "secret123",
+    }
+
+
+def test_fetch_raises_on_server_error(monkeypatch):
+    def fake_get(uri, headers, timeout):
+        return FakeResponse(ok=False)
+
+    monkeypatch.setattr(utils.requests, "get", fake_get)
+
+    with pytest.raises(requests.HTTPError):
+        fetch_databus_jsonld("https://databus.dbpedia.org/dbpedia/mappings")