diff --git a/img/snap-icon-128.png b/img/snap-icon-128.png
new file mode 100644
index 00000000..ebabbc23
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diff --git a/img/snap-icon-144.png b/img/snap-icon-144.png
new file mode 100644
index 00000000..fc1e9372
Binary files /dev/null and b/img/snap-icon-144.png differ
diff --git a/img/snap-icon-152.png b/img/snap-icon-152.png
new file mode 100644
index 00000000..1da2d45a
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diff --git a/img/snap-icon-192.png b/img/snap-icon-192.png
new file mode 100644
index 00000000..9be188a8
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diff --git a/img/snap-icon-256.png b/img/snap-icon-256.png
new file mode 100644
index 00000000..74852530
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diff --git a/img/snap-icon-512.png b/img/snap-icon-512.png
new file mode 100644
index 00000000..6a408622
Binary files /dev/null and b/img/snap-icon-512.png differ
diff --git a/manifest.json b/manifest.json
new file mode 100644
index 00000000..7ca95374
--- /dev/null
+++ b/manifest.json
@@ -0,0 +1,35 @@
+{
+  "name": "Snap! Build Your Own Blocks",
+  "short_name": "Snap!",
+  "icons": [{
+      "src": "img/snap-icon-128.png",
+      "sizes": "128x128",
+      "type": "image/png"
+    }, {
+      "src": "img/snap-icon-144.png",
+      "sizes": "144x144",
+      "type": "image/png"
+    }, {
+      "src": "img/snap-icon-152.png",
+      "sizes": "152x152",
+      "type": "image/png"
+    }, {
+      "src": "img/snap-icon-192.png",
+      "sizes": "192x192",
+      "type": "image/png",
+      "purpose": "any maskable"
+    }, {
+      "src": "img/snap-icon-256.png",
+      "sizes": "256x256",
+      "type": "image/png"
+    }, {
+      "src": "img/snap-icon-512.png",
+      "sizes": "512x512",
+      "type": "image/png"
+    }],
+  "lang": "en-US",
+  "start_url": "/snap.html",
+  "display": "standalone",
+  "background_color": "white",
+  "theme_color": "white"
+}
diff --git a/snap.html b/snap.html
index 9a990485..e8705bf7 100755
--- a/snap.html
+++ b/snap.html
@@ -1,10 +1,18 @@
 <!DOCTYPE html>
 <html>
     <head>
+        <title>Snap! 7 - dev - Build Your Own Blocks</title>
+        <link rel="icon" href="src/favicon.ico" type="image/x-icon">
+        <link rel="manifest" href="/manifest.json">
+        <link rel="apple-touch-icon" href="img/snap-icon-152.png">
         <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
         <meta name="viewport" content="width=device-width, initial-scale=1">
-        <title>Snap! 7 - dev - Build Your Own Blocks</title>
-        <link rel="icon" href="src/favicon.ico">
+        <meta name="theme-color" content="white"/>
+        <meta name="apple-mobile-web-app-capable" content="yes">
+        <meta name="apple-mobile-web-app-status-bar-style" content="black">
+        <meta name="apple-mobile-web-app-title" content="Snap!">
+        <meta name="msapplication-TileImage" content="img/snap-icon-144.png">
+        <meta name="msapplication-TileColor" content="#FFFFFF">
         <script src="src/morphic.js?version=2021-07-09"></script>
         <script src="src/symbols.js?version=2021-03-03"></script>
         <script src="src/widgets.js?version=2021-07-05"></script>
@@ -31,6 +39,9 @@
         <script>
             var world;
             window.onload = function () {
+                if ('serviceWorker' in navigator) {
+                    navigator.serviceWorker.register('./sw.js');
+                }
                 world = new WorldMorph(document.getElementById('world'));
                 new IDE_Morph().openIn(world);
                 loop();
diff --git a/sw.js b/sw.js
new file mode 100644
index 00000000..d02be80d
--- /dev/null
+++ b/sw.js
@@ -0,0 +1,46 @@
+var cacheName = 'snap-pwa';
+var filesToCache = [
+    '/',
+    '/snap.html',
+    '/src/morphic.js',
+    '/src/symbols.js',
+    '/src/widgets.js',
+    '/src/blocks.js',
+    '/src/threads.js',
+    '/src/objects.js',
+    '/src/scenes.js',
+    '/src/gui.js',
+    '/src/paint.js',
+    '/src/lists.js',
+    '/src/byob.js',
+    '/src/tables.js',
+    '/src/sketch.js',
+    '/src/video.js',
+    '/src/maps.js',
+    '/src/extensions.js',
+    '/src/xml.js',
+    '/src/store.js',
+    '/src/locale.js',
+    '/src/cloud.js',
+    '/src/api.js',
+    '/src/sha512.js',
+    '/src/FileSaver.min.js'
+];
+
+/* Start the service worker and cache all of the app's content */
+self.addEventListener('install', function(e) {
+  e.waitUntil(
+    caches.open(cacheName).then(function(cache) {
+      return cache.addAll(filesToCache);
+    })
+  );
+});
+
+/* Serve cached content when offline */
+self.addEventListener('fetch', function(e) {
+  e.respondWith(
+    caches.match(e.request).then(function(response) {
+      return response || fetch(e.request);
+    })
+  );
+});
