diff --git a/public/app.js b/public/app.js
new file mode 100644
index 0000000..886d72f
--- /dev/null
+++ b/public/app.js
@@ -0,0 +1,83 @@
+function openSignup() {
+  document.getElementById('signupModal').classList.add('active');
+  document.getElementById('signupForm').style.display = 'block';
+  document.getElementById('keyResult').style.display = 'none';
+  document.getElementById('signupEmail').value = '';
+  document.getElementById('signupError').style.display = 'none';
+  setTimeout(function() { document.getElementById('signupEmail').focus(); }, 100);
+}
+
+function closeSignup() {
+  document.getElementById('signupModal').classList.remove('active');
+}
+
+// Close on overlay click
+document.getElementById('signupModal').addEventListener('click', function(e) {
+  if (e.target === this) closeSignup();
+});
+
+// Submit on Enter
+document.getElementById('signupEmail').addEventListener('keydown', function(e) {
+  if (e.key === 'Enter') submitSignup();
+});
+
+async function submitSignup() {
+  var email = document.getElementById('signupEmail').value.trim();
+  var errEl = document.getElementById('signupError');
+  var btn = document.getElementById('signupBtn');
+
+  if (!email) {
+    errEl.textContent = 'Please enter your email.';
+    errEl.style.display = 'block';
+    return;
+  }
+
+  btn.textContent = 'Creating...';
+  btn.disabled = true;
+
+  try {
+    var res = await fetch('/v1/signup/free', {
+      method: 'POST',
+      headers: { 'Content-Type': 'application/json' },
+      body: JSON.stringify({ email: email })
+    });
+    var data = await res.json();
+
+    if (!res.ok) {
+      errEl.textContent = data.error || 'Something went wrong.';
+      errEl.style.display = 'block';
+      btn.textContent = 'Get API Key';
+      btn.disabled = false;
+      return;
+    }
+
+    // Show key
+    document.getElementById('signupForm').style.display = 'none';
+    document.getElementById('keyResult').style.display = 'block';
+    document.getElementById('apiKeyDisplay').textContent = data.apiKey;
+  } catch (err) {
+    errEl.textContent = 'Network error. Please try again.';
+    errEl.style.display = 'block';
+    btn.textContent = 'Get API Key';
+    btn.disabled = false;
+  }
+}
+
+function copyKey() {
+  var key = document.getElementById('apiKeyDisplay').textContent;
+  navigator.clipboard.writeText(key).then(function() {
+    document.querySelector('.copy-hint').textContent = '✓ Copied!';
+    setTimeout(function() { document.querySelector('.copy-hint').textContent = 'Click to copy'; }, 2000);
+  });
+}
+
+async function checkout() {
+  try {
+    var res = await fetch('/v1/billing/checkout', { method: 'POST' });
+    var data = await res.json();
+    if (data.url) window.location.href = data.url;
+    else alert('Something went wrong. Please try again.');
+  } catch (err) {
+    alert('Something went wrong. Please try again.');
+  }
+}
diff --git a/public/index.html b/public/index.html
index b7fd8fc..8dbfadc 100644
--- a/public/index.html
+++ b/public/index.html
@@ -238,90 +238,6 @@ footer { padding: 40px 0; text-align: center; color: var(--muted); font-size: 0.
   </div>
 </div>
 
-<script>
-function openSignup() {
-  document.getElementById('signupModal').classList.add('active');
-  document.getElementById('signupForm').style.display = 'block';
-  document.getElementById('keyResult').style.display = 'none';
-  document.getElementById('signupEmail').value = '';
-  document.getElementById('signupError').style.display = 'none';
-  setTimeout(() => document.getElementById('signupEmail').focus(), 100);
-}
-
-function closeSignup() {
-  document.getElementById('signupModal').classList.remove('active');
-}
-
-// Close on overlay click
-document.getElementById('signupModal').addEventListener('click', function(e) {
-  if (e.target === this) closeSignup();
-});
-
-// Submit on Enter
-document.getElementById('signupEmail').addEventListener('keydown', function(e) {
-  if (e.key === 'Enter') submitSignup();
-});
-
-async function submitSignup() {
-  const email = document.getElementById('signupEmail').value.trim();
-  const errEl = document.getElementById('signupError');
-  const btn = document.getElementById('signupBtn');
-
-  if (!email) {
-    errEl.textContent = 'Please enter your email.';
-    errEl.style.display = 'block';
-    return;
-  }
-
-  btn.textContent = 'Creating...';
-  btn.disabled = true;
-
-  try {
-    const res = await fetch('/v1/signup/free', {
-      method: 'POST',
-      headers: { 'Content-Type': 'application/json' },
-      body: JSON.stringify({ email })
-    });
-    const data = await res.json();
-
-    if (!res.ok) {
-      errEl.textContent = data.error || 'Something went wrong.';
-      errEl.style.display = 'block';
-      btn.textContent = 'Get API Key';
-      btn.disabled = false;
-      return;
-    }
-
-    // Show key
-    document.getElementById('signupForm').style.display = 'none';
-    document.getElementById('keyResult').style.display = 'block';
-    document.getElementById('apiKeyDisplay').textContent = data.apiKey;
-  } catch (err) {
-    errEl.textContent = 'Network error. Please try again.';
-    errEl.style.display = 'block';
-    btn.textContent = 'Get API Key';
-    btn.disabled = false;
-  }
-}
-
-function copyKey() {
-  const key = document.getElementById('apiKeyDisplay').textContent;
-  navigator.clipboard.writeText(key).then(() => {
-    document.querySelector('.copy-hint').textContent = '✓ Copied!';
-    setTimeout(() => document.querySelector('.copy-hint').textContent = 'Click to copy', 2000);
-  });
-}
-
-async function checkout() {
-  try {
-    const res = await fetch('/v1/billing/checkout', { method: 'POST' });
-    const data = await res.json();
-    if (data.url) window.location.href = data.url;
-    else alert('Something went wrong. Please try again.');
-  } catch (err) {
-    alert('Something went wrong. Please try again.');
-  }
-}
-</script>
+<script src="/app.js"></script>
 </body>
 </html>