diff --git a/App/admin.html b/App/admin.html
index 1969824..24c1fc1 100644
--- a/App/admin.html
+++ b/App/admin.html
@@ -104,5 +104,6 @@ api({action:'status'}).then(function(r) {
 document.getElementById('a-pass').addEventListener('keydown', function(e) { if(e.key==='Enter') doLogin(); });
 document.getElementById('a-pin').addEventListener('keydown', function(e) { if(e.key==='Enter') doVerify(); });
 </script>
+<script src="assets/js/version-tag.js" defer></script>
 </body>
 </html>
diff --git a/App/assets/js/version-tag.js b/App/assets/js/version-tag.js
new file mode 100644
index 0000000..a1825b4
--- /dev/null
+++ b/App/assets/js/version-tag.js
@@ -0,0 +1,59 @@
+/**
+ * GeoGraSim — Versions-Tag
+ * Rendert kleinen Hinweis rechts unten auf jeder Seite, damit lokal vs.
+ * produktiv schnell abzugleichen ist.
+ *
+ * Einbinden: <script src="assets/js/version-tag.js" defer></script>
+ *   (Pfad relativ zur Datei, die es einbindet. Im PHP-Wrapper aus BASE_PATH.)
+ *
+ * Liest version.json, zeigt Commit-SHA + Datum. Bei Fetch-Fehler (z.B.
+ * CORS, offline) zeigt es nichts — stumm, statt kaputt.
+ */
+(function () {
+  'use strict';
+  if (window.__GGS_VERSION_TAG_DONE__) return;
+  window.__GGS_VERSION_TAG_DONE__ = true;
+
+  // Pfad zur version.json ermitteln
+  var script = document.currentScript;
+  var versionUrl = 'version.json';
+  if (script && script.src) {
+    // Script-Src: .../assets/js/version-tag.js -> version.json auf gleicher Ebene wie assets/
+    var base = script.src.replace(/\/assets\/js\/version-tag\.js.*$/, '/');
+    versionUrl = base + 'version.json';
+  }
+
+  fetch(versionUrl, { cache: 'no-store' })
+    .then(function (r) { return r.ok ? r.json() : null; })
+    .then(function (v) {
+      if (!v) return;
+      var el = document.createElement('div');
+      el.className = 'ggs-version-tag';
+      el.title = 'Commit ' + v.commit + ' · ' + v.date;
+      el.innerHTML = '<span class="ggs-version-sha">' + v.commit + '</span>' +
+                     '<span class="ggs-version-date">' + v.date + '</span>';
+      Object.assign(el.style, {
+        position: 'fixed',
+        right: '6px',
+        bottom: '6px',
+        zIndex: '99998',
+        background: 'rgba(20,40,50,0.7)',
+        color: 'rgba(255,255,255,0.75)',
+        fontFamily: 'ui-monospace, Menlo, Consolas, monospace',
+        fontSize: '10px',
+        lineHeight: '1.2',
+        padding: '3px 7px',
+        borderRadius: '4px',
+        pointerEvents: 'auto',
+        userSelect: 'all',
+        cursor: 'help',
+        display: 'flex',
+        gap: '6px',
+        alignItems: 'center'
+      });
+      el.querySelector('.ggs-version-sha').style.fontWeight = '700';
+      el.querySelector('.ggs-version-date').style.opacity = '0.7';
+      document.body.appendChild(el);
+    })
+    .catch(function () { /* stumm */ });
+})();
diff --git a/App/index.html b/App/index.html
index 3733111..17919ed 100644
--- a/App/index.html
+++ b/App/index.html
@@ -727,5 +727,6 @@ function frame() {
 }
 frame();
 </script>
+<script src="assets/js/version-tag.js" defer></script>
 </body>
 </html>
diff --git a/App/login.html b/App/login.html
index bdcb777..76bbe2b 100644
--- a/App/login.html
+++ b/App/login.html
@@ -280,5 +280,6 @@ if (!resetToken) {
   });
 }
 </script>
+<script src="assets/js/version-tag.js" defer></script>
 </body>
 </html>
diff --git a/App/profil.html b/App/profil.html
index 0583c48..a4d3a59 100644
--- a/App/profil.html
+++ b/App/profil.html
@@ -229,5 +229,6 @@ async function deleteAccount() {
 
 loadProfile();
 </script>
+<script src="assets/js/version-tag.js" defer></script>
 </body>
 </html>
diff --git a/App/schueler.html b/App/schueler.html
index 0682a3d..03a1b64 100644
--- a/App/schueler.html
+++ b/App/schueler.html
@@ -297,5 +297,6 @@ async function renderProfile() {
 
 init();
 </script>
+<script src="assets/js/version-tag.js" defer></script>
 </body>
 </html>
diff --git a/App/teacher.html b/App/teacher.html
index af05e8a..e5a35ad 100644
--- a/App/teacher.html
+++ b/App/teacher.html
@@ -557,7 +557,8 @@ function printBatchTickets() {
     html += '<div class="ticket-row"><span class="ticket-label">Passwort:</span><span class="ticket-val">'+s.password+'</span></div>';
     html += '<div class="ticket-url">geograsim.at</div></div>';
   });
-  html += '</div></body></html>';
+  html += '</div><script src="assets/js/version-tag.js" defer></script>
+</body></html>';
   w.document.write(html); w.document.close();
 }
 
@@ -762,5 +763,6 @@ async function redeemLicenses() {
   loadLicenses();
 }
 </script>
+<script src="assets/js/version-tag.js" defer></script>
 </body>
 </html>
diff --git a/App/version.json b/App/version.json
new file mode 100644
index 0000000..53a3df7
--- /dev/null
+++ b/App/version.json
@@ -0,0 +1 @@
+{"commit":"b356c79","date":"2026-04-23 16:05 UTC"}