diff --git a/app.js b/app.js
index f26532f1..37bd4155 100644
--- a/app.js
+++ b/app.js
@@ -417,6 +417,12 @@ const script = {
     ],
     mesh_pool : [
         "&mesh/pool"
+    ],
+    cache : [
+        "main/service",
+    ],
+    service : [
+        "moto/service"
     ]
 };
 
@@ -474,6 +480,7 @@ function handleOptions(req, res, next) {
     } catch (e) {
         logger.log("ua parse error on : "+req.headers['user-agent']);
     }
+    res.setHeader("Service-Worker-Allowed", "/");
     if (req.method === 'OPTIONS') {
         addCorsHeaders(req, res);
         res.end();
diff --git a/src/main/service.js b/src/main/service.js
new file mode 100644
index 00000000..a69d9530
--- /dev/null
+++ b/src/main/service.js
@@ -0,0 +1,21 @@
+async function start_service_worker() {
+    // install service worker
+    console.log('registering service worker');
+
+    try {
+        // const reg = await navigator.serviceWorker.register("/src/moto/service.js?013", { scope: "/" });
+        const reg = await navigator.serviceWorker.register("/code/service.js?021", { scope: "/" });
+        if (reg.installing) {
+            console.log('service worker installing');
+        } else if (reg.waiting) {
+            console.log('service worker waiting');
+        } else if (reg.active) {
+            console.log('service worker active');
+        } else {
+            console.log({ service_worker: reg });
+        }
+    } catch (err) {
+        console.log('service worker registration failed');
+    }
+}
+if (navigator.serviceWorker) start_service_worker();
diff --git a/src/moto/service.js b/src/moto/service.js
new file mode 100644
index 00000000..c3ea235b
--- /dev/null
+++ b/src/moto/service.js
@@ -0,0 +1,99 @@
+console.log('service worker running 021');
+
+const addResourcesToCache = async (resources) => {
+    console.log('cache resources', resources);
+    const cache = await caches.open('v4');
+    await cache.addAll(resources);
+};
+
+const putInCache = async (request, response) => {
+    const cache = await caches.open('v4');
+    console.log('cache', request.request.url);
+    await cache.put(request, response);
+};
+
+const cacheFirst = async ({
+    request,
+    preloadResponsePromise,
+    fallbackUrl
+}) => {
+    // First try to get the resource from the cache
+    const responseFromCache = await caches.match(request);
+    if (responseFromCache) {
+        console.log('sw cached', request.url);
+        return responseFromCache;
+    }
+
+    // Next try to use the preloaded response, if it's there
+    // const preloadResponse = await preloadResponsePromise;
+    // if (preloadResponse) {
+    //     console.info('using preload response', preloadResponse);
+    //     putInCache(request, preloadResponse.clone());
+    //     return preloadResponse;
+    // }
+
+    // Next try to get the resource from the network
+    try {
+        console.log('fetch', request.request.url);
+        const responseFromNetwork = await fetch(request);
+        // response may be used only once
+        // we need to save clone to put one copy in cache
+        // and serve second one
+        putInCache(request, responseFromNetwork.clone());
+        return responseFromNetwork;
+    } catch (error) {
+        const fallbackResponse = await caches.match(fallbackUrl);
+        if (fallbackResponse) {
+            return fallbackResponse;
+        }
+        // when even the fallback response is not available,
+        // there is nothing we can do, but we must always
+        // return a Response object
+        return new Response('Network error happened', {
+            status: 408,
+            headers: {
+                'Content-Type': 'text/plain'
+            },
+        });
+    }
+};
+
+const enableNavigationPreload = async () => {
+    if (self.registration.navigationPreload) {
+        // Enable navigation preloads!
+        console.log('sw preload');
+        try {
+            await self.registration.navigationPreload.enable();
+        } catch (e) {
+            console.log('sw preload fail', e);
+        }
+
+    }
+};
+
+self.addEventListener('activate', (event) => {
+    console.log('sw activate preload');
+    // event.waitUntil(enableNavigationPreload());
+    // console.log('sw clients claim');
+    // event.waitUntil(clients.claim());
+});
+
+self.addEventListener('install', (event) => {
+    console.log('sw install');
+    event.waitUntil(
+        addResourcesToCache([
+            // '/',
+        ])
+    );
+});
+
+self.addEventListener('fetch', (event) => {
+    // console.log('sw fetch', event.request.url);
+    event.respondWith(
+        cacheFirst({
+            request: event.request,
+            preloadResponsePromise: event.preloadResponse,
+            fallbackUrl: '//static.grid.space/img/logo_gs.png',
+        })
+    );
+});
diff --git a/web/kiri/index.html b/web/kiri/index.html
index 074aed3b..78c26b61 100644
--- a/web/kiri/index.html
+++ b/web/kiri/index.html
@@ -19,7 +19,8 @@
     <link rel="apple-touch-icon" href="/kiri/favicon-mobile.png">
     <link rel="stylesheet" type="text/css" href="/kiri/index.css?{{version}}">
     <link href="/font/css/all.min.css" rel="stylesheet">
-    <script src="/font/js/all.min.js" crossorigin="anonymous" async></script>
+    <script src="/code/cache.js?{{version}}" defer></script>
+    <script src="/font/js/all.min.js" crossorigin="anonymous" defer></script>
     <script src="/code/kiri.js?{{version}}"></script>
 </head>
 <body>