diff --git a/nextcloud_mcp_server/client/base.py b/nextcloud_mcp_server/client/base.py
index 7e6a196b..8a538899 100644
--- a/nextcloud_mcp_server/client/base.py
+++ b/nextcloud_mcp_server/client/base.py
@@ -99,6 +99,21 @@ class BaseNextcloudClient(ABC):
         """Helper to get the base WebDAV path for the authenticated user."""
         return f"/remote.php/dav/files/{self.username}"
 
+    @staticmethod
+    def _resolve_url(url: str) -> str:
+        """Prefix bare ``/apps/...`` paths with ``/index.php``.
+
+        Pretty URLs (URL rewriting that strips ``index.php``) are an opt-in
+        Nextcloud feature; without them, ``/apps/<app>/...`` returns 404 — see
+        issue #732. ``/index.php/apps/<app>/...`` is the universal entry point
+        and works on every Nextcloud install regardless of web-server config,
+        so we route all app-API calls through it. ``/remote.php/dav/...`` and
+        ``/ocs/...`` have their own dedicated entry points and are unaffected.
+        """
+        if url.startswith("/apps/"):
+            return "/index.php" + url
+        return url
+
     @retry_on_429
     async def _make_request(self, method: str, url: str, **kwargs):
         """Common request wrapper with logging, tracing, and error handling.
@@ -111,6 +126,7 @@ class BaseNextcloudClient(ABC):
         Returns:
             Response object
         """
+        url = self._resolve_url(url)
         logger.debug(f"Making {method} request to {url}")
 
         # Start timer for metrics
diff --git a/tests/unit/client/test_base.py b/tests/unit/client/test_base.py
new file mode 100644
index 00000000..1697ea55
--- /dev/null
+++ b/tests/unit/client/test_base.py
@@ -0,0 +1,70 @@
+"""Unit tests for BaseNextcloudClient.
+
+These cover the URL prefix logic that routes ``/apps/...`` calls through the
+universal ``/index.php`` entry point so the server works on Nextcloud installs
+without Pretty URLs (issue #732).
+"""
+
+import pytest
+
+from nextcloud_mcp_server.client.base import BaseNextcloudClient
+
+pytestmark = pytest.mark.unit
+
+
+def test_apps_path_is_prefixed_with_index_php():
+    """Bare ``/apps/<app>/...`` 404s on Nextcloud without Pretty URLs; the
+    universal ``/index.php/apps/...`` form must be used instead.
+    """
+    assert (
+        BaseNextcloudClient._resolve_url("/apps/notes/api/v1/notes")
+        == "/index.php/apps/notes/api/v1/notes"
+    )
+    assert (
+        BaseNextcloudClient._resolve_url("/apps/deck/api/v1.0/boards/1/stacks/2/cards")
+        == "/index.php/apps/deck/api/v1.0/boards/1/stacks/2/cards"
+    )
+
+
+def test_remote_php_dav_unchanged():
+    """WebDAV/CalDAV/CardDAV paths use a dedicated entry point and don't need
+    rewriting — leave them alone so we don't break the working call sites.
+    """
+    assert (
+        BaseNextcloudClient._resolve_url("/remote.php/dav/files/alice/foo.txt")
+        == "/remote.php/dav/files/alice/foo.txt"
+    )
+
+
+def test_ocs_path_unchanged():
+    """The ``ocs/v2.php`` prefix is also a dedicated entry point — no rewrite."""
+    assert (
+        BaseNextcloudClient._resolve_url("/ocs/v2.php/cloud/users")
+        == "/ocs/v2.php/cloud/users"
+    )
+
+
+def test_already_prefixed_unchanged():
+    """If a caller already passed ``/index.php/apps/...`` we must not double-prefix."""
+    assert (
+        BaseNextcloudClient._resolve_url("/index.php/apps/notes/api/v1/notes")
+        == "/index.php/apps/notes/api/v1/notes"
+    )
+
+
+def test_absolute_url_unchanged():
+    """Absolute URLs (full ``https://...``) are pass-through; only path-prefix
+    matching is intentional, and an ``http://...`` URL doesn't start with
+    ``/apps/``.
+    """
+    assert (
+        BaseNextcloudClient._resolve_url("https://cloud.example.org/apps/notes")
+        == "https://cloud.example.org/apps/notes"
+    )
+
+
+def test_empty_or_unrelated_paths_unchanged():
+    """Defensive cases: empty strings, root, and non-apps paths must pass through."""
+    assert BaseNextcloudClient._resolve_url("") == ""
+    assert BaseNextcloudClient._resolve_url("/") == "/"
+    assert BaseNextcloudClient._resolve_url("/status.php") == "/status.php"