diff --git a/frontend/src/App.tsx b/frontend/src/App.tsx
index 3e29843..c7a9a87 100644
--- a/frontend/src/App.tsx
+++ b/frontend/src/App.tsx
@@ -30,6 +30,7 @@ import { ShareHub } from './pages/ShareHub';
 import { CompanyCardPage } from './pages/CompanyCardPage';
 import { HiringBoardPagePaginated } from './pages/HiringBoardPagePaginated';
 import { HiringAnalyticsPage } from './pages/HiringAnalyticsPage';
+import { NotFoundPage } from './pages/NotFoundPage';
 import './index.css';
 
 const queryClient = new QueryClient({
@@ -185,6 +186,7 @@ function AnimatedRoutes() {
         <Route path="founders" element={<FoundersPage />} />
         <Route path="roadmap" element={<RoadmapPage />} />
         <Route path="share" element={<ShareHub />} />
+        <Route path="*" element={<NotFoundPage />} />
       </Route>
     </Routes>
   );
diff --git a/frontend/src/pages/NotFoundPage.tsx b/frontend/src/pages/NotFoundPage.tsx
new file mode 100644
index 0000000..1e80a55
--- /dev/null
+++ b/frontend/src/pages/NotFoundPage.tsx
@@ -0,0 +1,51 @@
+import { Link, useLocation } from 'react-router-dom';
+import { Helmet } from 'react-helmet-async';
+import { ArrowLeft } from 'lucide-react';
+
+export function NotFoundPage() {
+  const location = useLocation();
+
+  return (
+    <div className="min-h-screen bg-background">
+      <Helmet>
+        <title>404 Not Found — ExploreYC</title>
+        <meta name="robots" content="noindex" />
+      </Helmet>
+      <div className="container mx-auto px-4 py-16 max-w-2xl">
+        <div className="font-mono text-muted-foreground text-sm mb-4">
+          $ cd <span className="text-[#FB651E]">{location.pathname}</span>
+        </div>
+        <div className="font-mono text-muted-foreground text-sm mb-8">
+          <span className="text-red-500">error:</span> no such file or directory
+        </div>
+
+        <h1 className="text-4xl font-bold mb-3">
+          <span className="font-mono text-[#FB651E]">&gt;</span> Page not found
+        </h1>
+        <p className="text-muted-foreground font-mono mb-8">
+          The page you're looking for doesn't exist on ExploreYC — yet.
+          If you followed a link from somewhere else, it might be stale.
+        </p>
+
+        <div className="flex flex-col gap-2 font-mono text-sm">
+          <div className="text-muted-foreground mb-2">Try one of these:</div>
+          <Link to="/" className="text-[#FB651E] hover:underline">→ Home (the YC company explorer)</Link>
+          <Link to="/hiring" className="text-[#FB651E] hover:underline">→ Hiring board</Link>
+          <Link to="/validator" className="text-[#FB651E] hover:underline">→ Idea validator</Link>
+          <Link to="/analytics/batches" className="text-[#FB651E] hover:underline">→ Batch analytics</Link>
+          <Link to="/founders" className="text-[#FB651E] hover:underline">→ For founders</Link>
+        </div>
+
+        <div className="mt-12 pt-6 border-t border-border">
+          <Link
+            to="/"
+            className="inline-flex items-center gap-2 text-sm font-mono text-muted-foreground hover:text-foreground transition-colors"
+          >
+            <ArrowLeft className="w-4 h-4" />
+            Back to home
+          </Link>
+        </div>
+      </div>
+    </div>
+  );
+}