diff --git a/package-lock.json b/package-lock.json
index 9ecb381d..b4e3de4e 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -2487,6 +2487,11 @@
         }
       }
     },
+    "idb-keyval": {
+      "version": "2.3.0",
+      "resolved": "https://registry.npmjs.org/idb-keyval/-/idb-keyval-2.3.0.tgz",
+      "integrity": "sha1-TURLgMP4b8vNUTIbTcvJJHxZSMA="
+    },
     "ieee754": {
       "version": "1.1.8",
       "resolved": "https://registry.npmjs.org/ieee754/-/ieee754-1.1.8.tgz",
diff --git a/package.json b/package.json
index 0ca9639c..3cb36e47 100644
--- a/package.json
+++ b/package.json
@@ -18,6 +18,7 @@
     "extract-text-webpack-plugin": "^3.0.2",
     "font-awesome-svg-png": "^1.2.2",
     "glob": "^7.1.2",
+    "idb-keyval": "^2.3.0",
     "node-fetch": "^1.7.3",
     "npm-run-all": "^4.1.2",
     "sapper": "^0.3.1",
diff --git a/routes/_utils/binary.js b/routes/_utils/binary.js
new file mode 100644
index 00000000..a14f023d
--- /dev/null
+++ b/routes/_utils/binary.js
@@ -0,0 +1,27 @@
+// from blob-util
+function blobToBinaryString(blob) {
+  return new Promise(function (resolve, reject) {
+    var reader = new FileReader();
+    var hasBinaryString = typeof reader.readAsBinaryString === 'function';
+    reader.onloadend = function (e) {
+      var result = e.target.result || '';
+      if (hasBinaryString) {
+        return resolve(result);
+      }
+      resolve(arrayBufferToBinaryString(result));
+    };
+    reader.onerror = reject;
+    if (hasBinaryString) {
+      reader.readAsBinaryString(blob);
+    } else {
+      reader.readAsArrayBuffer(blob);
+    }
+  });
+}
+
+export function blobToBase64(blob) {
+  return blobToBinaryString(blob).then(function (binary) {
+    // web-safe variant
+    return btoa(binary).replace(/\+/g, '-').replace(/\//g, '_').replace(/=+$/, '');
+  });
+}
\ No newline at end of file
diff --git a/routes/_utils/database.js b/routes/_utils/database.js
new file mode 100644
index 00000000..83429494
--- /dev/null
+++ b/routes/_utils/database.js
@@ -0,0 +1,21 @@
+import idbKeyVal from 'idb-keyval'
+import { blobToBase64 } from '../_utils/binary'
+
+let databasePromise
+
+if (process.browser) {
+  databasePromise = Promise.resolve().then(async () => {
+    let token = await idbKeyVal.get('secure_token')
+    if (!token) {
+      let array = new Uint32Array(1028)
+      crypto.getRandomValues(array);
+      let token = await blobToBase64(new Blob([array]))
+      await idbKeyVal.set('secure_token', token)
+    }
+    return idbKeyVal
+  })
+} else {
+  databasePromise = Promise.resolve()
+}
+
+export { databasePromise }
diff --git a/routes/_utils/mastodon.js b/routes/_utils/mastodon.js
new file mode 100644
index 00000000..e70a82b8
--- /dev/null
+++ b/routes/_utils/mastodon.js
@@ -0,0 +1,51 @@
+const WEBSITE = 'https://pinafore.social'
+const REDIRECT_URI = (typeof location !== 'undefined' ? location.origin : 'https://pinafore.social') + '/settings/add-instance'
+const SCOPES = 'read write follow'
+const CLIENT_NAME = 'Pinafore'
+
+export function registerApplication(instanceName) {
+  const url = `https://${instanceName}/api/v1/apps`
+  return fetch(url, {
+    method: 'POST',
+    headers: {
+      'Accept': 'application/json',
+      'Content-Type': 'application/json'
+    },
+    body: JSON.stringify({
+      client_name: CLIENT_NAME,
+      redirect_uris: REDIRECT_URI,
+      scopes: SCOPES,
+      website: WEBSITE
+    })
+  })
+}
+
+export function generateAuthLink(instanceName, clientId) {
+  let url = `https://${instanceName}/oauth/authorize`
+
+  let params = new URLSearchParams()
+  params.set('client_id', clientId)
+  params.set('redirect_uri', REDIRECT_URI)
+  params.set('response_type', 'code')
+  params.set('scope', SCOPES)
+  url += '?' + params.toString()
+  return url
+}
+
+export function getAccessTokenFromAuthCode(instanceName, clientId, clientSecret, code) {
+  let url = `https://${instanceName}/oauth/token`
+  return fetch(url, {
+    method: 'POST',
+    headers: {
+      'Accept': 'application/json',
+      'Content-Type': 'application/json'
+    },
+    body: JSON.stringify({
+      client_id: clientId,
+      client_secret: clientSecret,
+      redirect_uri: REDIRECT_URI,
+      grant_type: 'authorization_code',
+      code: code
+    })
+  })
+}
\ No newline at end of file
diff --git a/routes/settings/add-instance.html b/routes/settings/add-instance.html
index 505eed94..2088c148 100644
--- a/routes/settings/add-instance.html
+++ b/routes/settings/add-instance.html
@@ -16,7 +16,14 @@
   <p>Don't have an instance? <a href="https://joinmastodon.org">Join Mastodon!</a></p>
 </Layout>
 <style>
+  @media (max-width: 767px) {
+    input {
+      width: 90%;
+    }
+  }
+
   input {
+    width: 250px;
   }
 
   form {
@@ -30,11 +37,39 @@
     display: block;
     margin: 20px 5px;
   }
+
+
+
 </style>
 <script>
   import Layout from '../_components/Layout.html';
+  import { registerApplication, generateAuthLink, getAccessTokenFromAuthCode } from '../_utils/mastodon'
+  import { databasePromise } from '../_utils/database'
 
   export default {
+    oncreate: function () {
+      if (process.browser) {
+        (async () => {
+          let params = new URLSearchParams(location.search)
+          if (params.has('code')) {
+            let db = await databasePromise
+            let instanceData = await db.get('instance')
+            this.set({instanceName: instanceData.instanceName})
+            let code = params.get('code')
+            instanceData.code = code
+            let response = await (await getAccessTokenFromAuthCode(
+              instanceData.instanceName,
+              instanceData.client_id,
+              instanceData.client_secret,
+              instanceData.code
+            )).json()
+            instanceData = Object.assign(instanceData, response)
+            await db.set(`instance`, instanceData)
+            console.log('response', response)
+          }
+        })()
+      }
+    },
     components: {
       Layout
     },
@@ -42,11 +77,17 @@
       instanceName: ''
     }),
     methods: {
-      handleSubmit(event) {
+      handleSubmit: async function(event) {
         event.preventDefault()
         let instanceName = this.get('instanceName')
-        alert(instanceName)
-      }
+        instanceName = instanceName.replace(/^https?:\/\//, '').replace('/$', '')
+        let data = await (await registerApplication(instanceName)).json()
+        let db = await databasePromise
+        data.instanceName = instanceName
+        await db.set(`instance`, data)
+        let oauthUrl = generateAuthLink(instanceName, data.client_id)
+        document.location.href = oauthUrl
+      },
     }
   }
 </script>
\ No newline at end of file
diff --git a/templates/2xx.html b/templates/2xx.html
index a92fd3ec..42d21e8e 100644
--- a/templates/2xx.html
+++ b/templates/2xx.html
@@ -10,7 +10,9 @@
 	<link rel='icon' type='image/png' href='/favicon.png'>
 
 	<script>
-		if (!location.origin.match('localhost') && 'serviceWorker' in navigator) {
+		if (!location.origin.match('localhost') &&
+      !location.origin.match('127.0.0.1') &&
+			  'serviceWorker' in navigator) {
 			navigator.serviceWorker.register('/service-worker.js');
 		}
 	</script>