diff --git a/shell.nix b/shell.nix
index 8c3f8b97e..7b3fd32e9 100644
--- a/shell.nix
+++ b/shell.nix
@@ -9,7 +9,8 @@ let
 
   haskellPackages = pkgs.haskellPackages;
 
-  oauth2Flake = (builtins.getFlake "git+https://gitlab.uniworx.de/mosbach/oauth2-mock-server/?rev=d47908b4f7883b4b485abf1ee06645495ccdc7b3&ref=user-queries").packages.x86_64-linux;
+  oauth2Flake = (builtins.getFlake "git+https://gitlab.uniworx.de/mosbach/oauth2-mock-server/?rev=45debf40cd171f78a4de38f608a6cfd3be73b91a&ref=oidc").packages.x86_64-linux;
+
 
   oauth2MockServer = oauth2Flake.default;
   mkOauth2DB = oauth2Flake.mkOauth2DB;
diff --git a/src/Foundation/Instances.hs b/src/Foundation/Instances.hs
index 20d10b2de..49b6b5de9 100644
--- a/src/Foundation/Instances.hs
+++ b/src/Foundation/Instances.hs
@@ -42,6 +42,8 @@ import Foundation.DB
 
 import Network.Wai.Parse (lbsBackEnd)
 
+import System.Environment (lookupEnv)
+
 import UnliftIO.Pool (withResource)
 
 import qualified Control.Monad.State.Class as State
@@ -136,6 +138,12 @@ instance YesodAuth UniWorX where
         plugins <- getsYesod authPlugins
         $logDebugS "Auth" $ "Enabled plugins: " <> Text.intercalate ", " (map apName plugins)
 
+#ifdef DEVELOPMENT
+        mPort <- liftIO $ lookupEnv "OAUTH2_SERVER_PORT"
+#else
+        let mPort = Nothing
+#endif
+
         setTitleI MsgLoginTitle
         $(widgetFile "login")
 
diff --git a/templates/login.hamlet b/templates/login.hamlet
index bb3ee704e..e5dc2706f 100644
--- a/templates/login.hamlet
+++ b/templates/login.hamlet
@@ -1,6 +1,6 @@
 $newline never
 
-$# SPDX-FileCopyrightText: 2022-2024 Gregor Kleen <gregor.kleen@ifi.lmu.de>,David Mosbach <david.mosbach@uniworx.de>
+$# SPDX-FileCopyrightText: 2022-2024 Gregor Kleen <gregor.kleen@ifi.lmu.de>, David Mosbach <david.mosbach@uniworx.de>
 $#
 $# SPDX-License-Identifier: AGPL-3.0-or-later
 
@@ -26,3 +26,8 @@ $forall AuthPlugin{apName, apLogin} <- plugins
     <section>
       <h2>_{MsgDummyLoginTitle}
       ^{apLogin toParent}
+$maybe port <- mPort
+  <section>
+    <h2>SSO Dev Test
+    <a href=http://localhost:#{port}/test-sso>Test login via single sign-on
+