diff --git a/viewer/src/AppLayout.tsx b/viewer/src/AppLayout.tsx
index 6a224b3..36041c5 100644
--- a/viewer/src/AppLayout.tsx
+++ b/viewer/src/AppLayout.tsx
@@ -140,6 +140,10 @@ export function AppLayout() {
       )}
 
       <Outlet context={{ events, exclusions } satisfies LayoutContext} />
+
+      <footer style={{ marginTop: "2rem", color: "#999", fontSize: "0.75rem" }}>
+        rev: {__GIT_REVISION__}
+      </footer>
     </div>
   );
 }
diff --git a/viewer/src/vite-env.d.ts b/viewer/src/vite-env.d.ts
index 11f02fe..4016465 100644
--- a/viewer/src/vite-env.d.ts
+++ b/viewer/src/vite-env.d.ts
@@ -1 +1,3 @@
 /// <reference types="vite/client" />
+
+declare const __GIT_REVISION__: string;
diff --git a/viewer/vite.config.ts b/viewer/vite.config.ts
index 95bcfe1..f00d5a3 100644
--- a/viewer/vite.config.ts
+++ b/viewer/vite.config.ts
@@ -1,7 +1,19 @@
+import { execSync } from "node:child_process";
 import { defineConfig } from "vite";
 import react from "@vitejs/plugin-react";
 
+const gitRevision = (() => {
+  try {
+    return execSync("git rev-parse --short HEAD").toString().trim();
+  } catch {
+    return "unknown";
+  }
+})();
+
 export default defineConfig({
   plugins: [react()],
   base: "/eventstats/",
+  define: {
+    __GIT_REVISION__: JSON.stringify(gitRevision),
+  },
 });