diff --git a/public/unsupported.html b/public/unsupported.html
new file mode 100644
index 000000000..d83f11248
--- /dev/null
+++ b/public/unsupported.html
@@ -0,0 +1,18 @@
+<!DOCTYPE html>
+<html style="height: 100%">
+  <head>
+    <title>Unsupported browser</title>
+  </head>
+  <body style="height: 100%; margin: 0;">
+    <table style="width: 100%; height: 100%; border-collapse: collapse;">
+      <tr>
+        <td style="vertical-align: middle; text-align: center;">
+          <div style="display: inline-block;">
+            <img src="./unsupported.png">
+            <h3>Your browser is not supported. Please, update it or use our <a href="http://telegram.org/dl" target="_blank">native clients</a></h3>
+          </div>
+        </td>
+      </tr>
+    </table>
+  </body>
+</html>
diff --git a/public/unsupported.png b/public/unsupported.png
new file mode 100644
index 000000000..945bc1788
Binary files /dev/null and b/public/unsupported.png differ
diff --git a/src/index.html b/src/index.html
index db01b4536..e415ec351 100644
--- a/src/index.html
+++ b/src/index.html
@@ -4,11 +4,15 @@
 <head>
   <meta charset="UTF-8">
 
-  <title><%= htmlWebpackPlugin.options.appTitle %></title>
+  <title>
+    <%= htmlWebpackPlugin.options.appTitle %>
+  </title>
 
   <meta name="title" content="<%= htmlWebpackPlugin.options.appTitle %>">
-  <meta name="description" content="Telegram is a cloud-based mobile and desktop messaging app with a focus on security and speed.">
-  <meta name="viewport" content="width=device-width, initial-scale=1, maximum-scale=1.0, user-scalable=no, shrink-to-fit=no, viewport-fit=cover">
+  <meta name="description"
+    content="Telegram is a cloud-based mobile and desktop messaging app with a focus on security and speed.">
+  <meta name="viewport"
+    content="width=device-width, initial-scale=1, maximum-scale=1.0, user-scalable=no, shrink-to-fit=no, viewport-fit=cover">
   <meta name="mobile-web-app-capable" content="yes">
   <meta name="mobile-web-app-title" content="<%= htmlWebpackPlugin.options.appTitle %>">
   <meta name="apple-mobile-web-app-capable" content="yes">
@@ -23,14 +27,16 @@
   <meta property="og:type" content="website">
   <meta property="og:url" content="<%= htmlWebpackPlugin.options.baseUrl %>">
   <meta property="og:title" content="<%= htmlWebpackPlugin.options.appTitle %>">
-  <meta property="og:description" content="Telegram is a cloud-based mobile and desktop messaging app with a focus on security and speed.">
+  <meta property="og:description"
+    content="Telegram is a cloud-based mobile and desktop messaging app with a focus on security and speed.">
   <meta property="og:image" content="./<%= htmlWebpackPlugin.options.mainIcon %>.png">
 
   <!-- Twitter -->
   <meta property="twitter:card" content="summary_large_image">
   <meta property="twitter:url" content="<%= htmlWebpackPlugin.options.baseUrl %>">
   <meta property="twitter:title" content="<%= htmlWebpackPlugin.options.appTitle %>">
-  <meta property="twitter:description" content="Telegram is a cloud-based mobile and desktop messaging app with a focus on security and speed.">
+  <meta property="twitter:description"
+    content="Telegram is a cloud-based mobile and desktop messaging app with a focus on security and speed.">
   <meta property="twitter:image" content="./<%= htmlWebpackPlugin.options.mainIcon %>.png">
 
   <link rel="canonical" href="https://web.telegram.org/">
@@ -62,5 +68,31 @@
     <p>Please, enable JavaScript to open the app.</p>
   </noscript>
   <div id="portals"></div>
+  <script>
+    function compatTest() {
+      var hasPromise = typeof Promise !== 'undefined';
+      var hasWebSockets = typeof WebSocket !== 'undefined';
+      var hasWebCrypto = window.crypto && typeof window.crypto.subtle !== 'undefined';
+      var hasObjectFromEntries = typeof Object.fromEntries !== 'undefined';
+
+      var isCompatible = hasPromise && hasWebSockets && hasWebCrypto && hasObjectFromEntries;
+
+      if (isCompatible) {
+        window.isCompatTestPassed = true;
+        return;
+      }
+
+      console.warn('Compatibility test report:');
+      console.warn('Promise', hasPromise);
+      console.warn('WebSocket', hasWebSockets);
+      console.warn('WebCrypto', hasWebCrypto);
+      console.warn('Object.fromEntries', hasObjectFromEntries);
+
+      document.body.innerHTML = '<iframe src="./unsupported.html" width="100%" height="100%">';
+    }
+
+    compatTest();
+  </script>
 </body>
+
 </html>
diff --git a/src/index.tsx b/src/index.tsx
index 2b4cfe751..eaa2af939 100644
--- a/src/index.tsx
+++ b/src/index.tsx
@@ -36,6 +36,8 @@ async function init() {
     console.log('>>> INIT');
   }
 
+  if (!(window as any).isCompatTestPassed) return;
+
   if (IS_MULTITAB_SUPPORTED) {
     subscribeToMultitabBroadcastChannel();
 
