diff --git a/public/app.js b/public/app.js
index ce2e351..0f526cf 100644
--- a/public/app.js
+++ b/public/app.js
@@ -477,3 +477,39 @@ document.addEventListener('DOMContentLoaded', function() {
     el.addEventListener('click', function(e) { e.preventDefault(); openEmailChange(); });
   });
 });
+
+// === Accessibility: Escape key closes modals, focus trapping ===
+(function() {
+  function getActiveModal() {
+    var modals = ['signupModal', 'recoverModal', 'emailChangeModal'];
+    for (var i = 0; i < modals.length; i++) {
+      var m = document.getElementById(modals[i]);
+      if (m && m.classList.contains('active')) return m;
+    }
+    return null;
+  }
+
+  function closeActiveModal() {
+    var m = getActiveModal();
+    if (!m) return;
+    m.classList.remove('active');
+  }
+
+  document.addEventListener('keydown', function(e) {
+    if (e.key === 'Escape') closeActiveModal();
+
+    // Focus trap inside active modal
+    if (e.key === 'Tab') {
+      var modal = getActiveModal();
+      if (!modal) return;
+      var focusable = modal.querySelectorAll('button:not([disabled]), input:not([disabled]), a[href], [tabindex]:not([tabindex="-1"])');
+      if (focusable.length === 0) return;
+      var first = focusable[0], last = focusable[focusable.length - 1];
+      if (e.shiftKey) {
+        if (document.activeElement === first) { e.preventDefault(); last.focus(); }
+      } else {
+        if (document.activeElement === last) { e.preventDefault(); first.focus(); }
+      }
+    }
+  });
+})();
diff --git a/public/index.html b/public/index.html
index 6a4f860..659e233 100644
--- a/public/index.html
+++ b/public/index.html
@@ -5,6 +5,15 @@
 <meta name="viewport" content="width=device-width, initial-scale=1.0">
 <title>DocFast — HTML & Markdown to PDF API</title>
 <meta name="description" content="Convert HTML and Markdown to beautiful PDFs with a simple API call. Built-in invoice templates. Fast, reliable, developer-friendly.">
+<meta property="og:title" content="DocFast — HTML & Markdown to PDF API">
+<meta property="og:description" content="Convert HTML and Markdown to beautiful PDFs with a simple API call. Fast, reliable, developer-friendly.">
+<meta property="og:type" content="website">
+<meta property="og:url" content="https://docfast.dev">
+<meta property="og:image" content="https://docfast.dev/og-image.png">
+<meta name="twitter:card" content="summary_large_image">
+<meta name="twitter:title" content="DocFast — HTML & Markdown to PDF API">
+<meta name="twitter:description" content="Convert HTML and Markdown to beautiful PDFs with a simple API call.">
+<link rel="canonical" href="https://docfast.dev">
 <link rel="icon" href="data:image/svg+xml,<svg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 100 100'><text y='.9em' font-size='90'>⚡</text></svg>">
 <style>
 *, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
@@ -231,6 +240,9 @@ html, body {
 #emailChangeLoading.active { display: flex; flex-direction: column; align-items: center; padding: 40px 0; text-align: center; }
 #emailChangeResult.active { display: block; }
 #emailChangeVerify.active { display: block; }
+
+/* Focus-visible for accessibility */
+.btn:focus-visible, a:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }
 </style>
 <link rel="preconnect" href="https://fonts.googleapis.com">
 <link rel="preconnect" href="https://fonts.gstatic.com" crossorigin>
@@ -238,7 +250,7 @@ html, body {
 </head>
 <body>
 
-<nav>
+<nav aria-label="Main navigation">
   <div class="container">
     <div class="logo">⚡ Doc<span>Fast</span></div>
     <div class="nav-links">
@@ -249,7 +261,7 @@ html, body {
   </div>
 </nav>
 
-<section class="hero">
+<main class="hero" role="main">
   <div class="container">
     <div class="badge">🚀 Simple PDF API for Developers</div>
     <h1>HTML to <span class="gradient">PDF</span><br>in one API call</h1>
@@ -262,7 +274,7 @@ html, body {
 
     <div class="code-section">
       <div class="code-header">
-        <div class="code-dots"><span></span><span></span><span></span></div>
+        <div class="code-dots" aria-hidden="true"><span></span><span></span><span></span></div>
         <span class="code-label">terminal</span>
       </div>
       <div class="code-block">
@@ -275,7 +287,7 @@ html, body {
       </div>
     </div>
   </div>
-</section>
+</main>
 
 <section class="trust">
   <div class="container">
@@ -306,32 +318,32 @@ html, body {
     <p class="section-sub">A complete PDF generation API. No SDKs, no dependencies, no setup.</p>
     <div class="features-grid">
       <div class="feature-card">
-        <div class="feature-icon">⚡</div>
+        <div class="feature-icon" aria-hidden="true">⚡</div>
         <h3>Sub-second Speed</h3>
         <p>Persistent browser pool — no cold starts. Your PDFs are ready before your spinner shows.</p>
       </div>
       <div class="feature-card">
-        <div class="feature-icon">🎨</div>
+        <div class="feature-icon" aria-hidden="true">🎨</div>
         <h3>Pixel-perfect Output</h3>
         <p>Full CSS support including flexbox, grid, and custom fonts. Your brand, your PDFs.</p>
       </div>
       <div class="feature-card">
-        <div class="feature-icon">📄</div>
+        <div class="feature-icon" aria-hidden="true">📄</div>
         <h3>Built-in Templates</h3>
         <p>Invoice and receipt templates out of the box. Pass JSON data, get beautiful PDFs.</p>
       </div>
       <div class="feature-card">
-        <div class="feature-icon">🔧</div>
+        <div class="feature-icon" aria-hidden="true">🔧</div>
         <h3>Dead-simple API</h3>
         <p>REST API. JSON in, PDF out. Works with curl, Python, Node, Go — anything with HTTP.</p>
       </div>
       <div class="feature-card">
-        <div class="feature-icon">📐</div>
+        <div class="feature-icon" aria-hidden="true">📐</div>
         <h3>Fully Configurable</h3>
         <p>A4, Letter, custom sizes. Portrait or landscape. Headers, footers, and margins.</p>
       </div>
       <div class="feature-card">
-        <div class="feature-icon">🔒</div>
+        <div class="feature-icon" aria-hidden="true">🔒</div>
         <h3>Secure by Default</h3>
         <p>HTTPS only. Rate limiting. No data stored. PDFs stream directly — nothing touches disk.</p>
       </div>
@@ -372,7 +384,7 @@ html, body {
   </div>
 </section>
 
-<footer>
+<footer aria-label="Footer">
   <div class="container">
     <div class="footer-left">© 2026 DocFast. Fast PDF generation for developers.</div>
     <div class="footer-links">
@@ -384,7 +396,7 @@ html, body {
 </footer>
 
 <!-- Signup Modal -->
-<div class="modal-overlay" id="signupModal">
+<div class="modal-overlay" id="signupModal" role="dialog" aria-label="Sign up for API key">
   <div class="modal">
     <button class="close" id="btn-close-signup">&times;</button>
 
@@ -411,7 +423,7 @@ html, body {
       <p style="margin-top:16px;color:var(--muted);font-size:0.8rem;text-align:center;">Code expires in 15 minutes</p>
     </div>
 
-    <div id="signupResult">
+    <div id="signupResult" aria-live="polite">
       <h2>🚀 Your API key is ready!</h2>
       <div class="warning-box">
         <span class="icon">⚠️</span>
@@ -428,7 +440,7 @@ html, body {
 
 
 <!-- Recovery Modal -->
-<div class="modal-overlay" id="recoverModal">
+<div class="modal-overlay" id="recoverModal" role="dialog" aria-label="Recover API key">
   <div class="modal">
     <button class="close" id="btn-close-recover">&times;</button>
 
@@ -455,7 +467,7 @@ html, body {
       <p style="margin-top:16px;color:var(--muted);font-size:0.8rem;text-align:center;">Code expires in 15 minutes</p>
     </div>
 
-    <div id="recoverResult">
+    <div id="recoverResult" aria-live="polite">
       <h2>🔑 Your API key</h2>
       <div class="warning-box">
         <span class="icon">⚠️</span>
@@ -472,7 +484,7 @@ html, body {
 
 
 <!-- Email Change Modal -->
-<div class="modal-overlay" id="emailChangeModal">
+<div class="modal-overlay" id="emailChangeModal" role="dialog" aria-label="Change email">
   <div class="modal">
     <button class="close" id="btn-close-email-change">&times;</button>
 
diff --git a/public/og-image.png b/public/og-image.png
new file mode 100644
index 0000000..ac80686
Binary files /dev/null and b/public/og-image.png differ
diff --git a/public/og-image.svg b/public/og-image.svg
new file mode 100644
index 0000000..d84e492
--- /dev/null
+++ b/public/og-image.svg
@@ -0,0 +1,13 @@
+<svg xmlns="http://www.w3.org/2000/svg" width="1200" height="630" viewBox="0 0 1200 630">
+  <rect width="1200" height="630" fill="#0b0d11"/>
+  <rect x="0" y="0" width="1200" height="630" fill="url(#glow)" opacity="0.3"/>
+  <defs>
+    <radialGradient id="glow" cx="50%" cy="50%" r="50%">
+      <stop offset="0%" stop-color="#34d399" stop-opacity="0.2"/>
+      <stop offset="100%" stop-color="#0b0d11" stop-opacity="0"/>
+    </radialGradient>
+  </defs>
+  <text x="600" y="270" text-anchor="middle" font-family="Inter, -apple-system, sans-serif" font-size="80" font-weight="800" fill="#e4e7ed">⚡ Doc<tspan fill="#34d399">Fast</tspan></text>
+  <text x="600" y="370" text-anchor="middle" font-family="Inter, -apple-system, sans-serif" font-size="36" font-weight="400" fill="#7a8194">HTML &amp; Markdown to PDF API</text>
+  <rect x="400" y="420" width="400" height="4" rx="2" fill="#34d399" opacity="0.5"/>
+</svg>
diff --git a/public/robots.txt b/public/robots.txt
new file mode 100644
index 0000000..74f955a
--- /dev/null
+++ b/public/robots.txt
@@ -0,0 +1,6 @@
+User-agent: *
+Allow: /
+Disallow: /v1/
+Disallow: /api
+Disallow: /health
+Sitemap: https://docfast.dev/sitemap.xml
diff --git a/public/sitemap.xml b/public/sitemap.xml
new file mode 100644
index 0000000..a891bea
--- /dev/null
+++ b/public/sitemap.xml
@@ -0,0 +1,5 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<urlset xmlns="http://www.sitemapns.org/schemas/sitemap/0.9">
+  <url><loc>https://docfast.dev/</loc><changefreq>weekly</changefreq><priority>1.0</priority></url>
+  <url><loc>https://docfast.dev/docs</loc><changefreq>weekly</changefreq><priority>0.8</priority></url>
+</urlset>
