diff --git a/apps/visualizer/src/App.tsx b/apps/visualizer/src/App.tsx
index de07e8e..503e78f 100644
--- a/apps/visualizer/src/App.tsx
+++ b/apps/visualizer/src/App.tsx
@@ -9,6 +9,7 @@ import Tabs from './ui/Tabs';
 import MarketHeader from './features/market/MarketHeader';
 import Button from './ui/Button';
 import TopNav from './layout/TopNav';
+import AuthStatus from './layout/AuthStatus';
 
 function envNumber(name: string, fallback: number): number {
   const v = (import.meta as any).env?.[name];
@@ -155,7 +156,7 @@ export default function App() {
 
   return (
     <AppShell
-      header={<TopNav active="trade" />}
+      header={<TopNav active="trade" rightSlot={<AuthStatus />} />}
       top={<TickerBar items={topItems} />}
       main={
         <div className="tradeMain">
diff --git a/apps/visualizer/src/layout/AuthStatus.tsx b/apps/visualizer/src/layout/AuthStatus.tsx
new file mode 100644
index 0000000..9ed3d4d
--- /dev/null
+++ b/apps/visualizer/src/layout/AuthStatus.tsx
@@ -0,0 +1,55 @@
+import { useEffect, useState } from 'react';
+import Button from '../ui/Button';
+
+type WhoamiResponse = {
+  ok?: boolean;
+  user?: string | null;
+};
+
+export default function AuthStatus() {
+  const [user, setUser] = useState<string | null>(null);
+  const [loading, setLoading] = useState(true);
+
+  useEffect(() => {
+    let cancelled = false;
+
+    fetch('/whoami', { cache: 'no-store' })
+      .then(async (res) => {
+        const json = (await res.json().catch(() => null)) as WhoamiResponse | null;
+        const u = typeof json?.user === 'string' ? json.user.trim() : '';
+        return u || null;
+      })
+      .then((u) => {
+        if (cancelled) return;
+        setUser(u);
+      })
+      .catch(() => {
+        if (cancelled) return;
+        setUser(null);
+      })
+      .finally(() => {
+        if (cancelled) return;
+        setLoading(false);
+      });
+
+    return () => {
+      cancelled = true;
+    };
+  }, []);
+
+  const logout = () => {
+    window.location.href = '/logout';
+  };
+
+  return (
+    <div className="authStatus">
+      <Button size="sm" variant="ghost" type="button" onClick={logout}>
+        Wyloguj
+      </Button>
+      <div className="topNav__account">
+        <div className="topNav__accountName">{loading ? '…' : user || 'unknown'}</div>
+        <div className="topNav__accountSub">zalogowany</div>
+      </div>
+    </div>
+  );
+}
diff --git a/apps/visualizer/src/styles.css b/apps/visualizer/src/styles.css
index 860b3fd..0dbf625 100644
--- a/apps/visualizer/src/styles.css
+++ b/apps/visualizer/src/styles.css
@@ -282,6 +282,12 @@ a:hover {
   align-items: center;
 }
 
+.authStatus {
+  display: flex;
+  gap: 10px;
+  align-items: center;
+}
+
 .topNav__iconBtn {
   background: rgba(255, 255, 255, 0.02);
   border: 1px solid rgba(255, 255, 255, 0.12);
diff --git a/services/frontend/server.mjs b/services/frontend/server.mjs
index 449ce1a..f324208 100644
--- a/services/frontend/server.mjs
+++ b/services/frontend/server.mjs
@@ -19,6 +19,9 @@ const BASIC_AUTH_MODE = String(process.env.BASIC_AUTH_MODE || 'on')
   .trim()
   .toLowerCase();
 const BASIC_AUTH_ENABLED = !['off', 'false', '0', 'disabled', 'none'].includes(BASIC_AUTH_MODE);
+const AUTH_USER_HEADER = String(process.env.AUTH_USER_HEADER || 'x-trade-user')
+  .trim()
+  .toLowerCase();
 
 function readJson(filePath) {
   const raw = fs.readFileSync(filePath, 'utf8');
@@ -54,6 +57,10 @@ function send(res, status, headers, body) {
   res.end(body);
 }
 
+function sendJson(res, status, body) {
+  send(res, status, { 'content-type': 'application/json; charset=utf-8', 'cache-control': 'no-store' }, JSON.stringify(body));
+}
+
 function basicAuthRequired(res) {
   res.setHeader('www-authenticate', 'Basic realm="trade"');
   send(res, 401, { 'content-type': 'text/plain; charset=utf-8' }, 'unauthorized');
@@ -169,6 +176,17 @@ function stripHopByHopHeaders(headers) {
   return out;
 }
 
+function readHeader(req, name) {
+  const v = req.headers[String(name).toLowerCase()];
+  return Array.isArray(v) ? v[0] : v;
+}
+
+function resolveAuthUser(req) {
+  const user = readHeader(req, AUTH_USER_HEADER) || readHeader(req, 'x-webauth-user');
+  const value = typeof user === 'string' ? user.trim() : '';
+  return value || null;
+}
+
 function proxyApi(req, res, apiReadToken) {
   const upstreamBase = new URL(API_UPSTREAM);
   const inUrl = new URL(req.url || '/', `http://${req.headers.host || 'localhost'}`);
@@ -230,6 +248,20 @@ function handler(req, res) {
     return;
   }
 
+  const url = new URL(req.url || '/', `http://${req.headers.host || 'localhost'}`);
+  if (req.method === 'GET' && url.pathname === '/whoami') {
+    sendJson(res, 200, { ok: true, user: resolveAuthUser(req) });
+    return;
+  }
+
+  if (req.method === 'GET' && url.pathname === '/logout') {
+    // NOTE: With HTTP basic auth handled upstream (Traefik), browser "logout" is best-effort.
+    // This endpoint forces a 401 so the browser prompts again, allowing the user to switch accounts.
+    res.setHeader('www-authenticate', 'Basic realm="trade"');
+    send(res, 401, { 'content-type': 'text/plain; charset=utf-8', 'cache-control': 'no-store' }, 'logged_out');
+    return;
+  }
+
   if (BASIC_AUTH_ENABLED) {
     let creds;
     try {
@@ -272,6 +304,7 @@ server.listen(PORT, () => {
         basicAuthFile: BASIC_AUTH_FILE,
         basicAuthMode: BASIC_AUTH_MODE,
         apiReadTokenFile: API_READ_TOKEN_FILE,
+        authUserHeader: AUTH_USER_HEADER,
       },
       null,
       2