diff --git a/extension/common.js b/extension/common.js
index 98b3e4c..2f56a73 100644
--- a/extension/common.js
+++ b/extension/common.js
@@ -18,21 +18,19 @@ chrome.tabs.onCreated.addListener(tab => {
 });
 
 const prefs = {
-  ua: '',
-  blacklist: [],
-  whitelist: [],
-  custom: {},
-  siblings: {
-    'www.google.com': 0,
-    'www.youtube.com': 0
-  }, // a list of domains that are considered siblings (use same index for all)
-  mode: 'blacklist',
-  color: '#777',
-  cache: true,
-  exactMatch: false,
-  protected: ['google.com/recaptcha', 'gstatic.com/recaptcha'],
-  parser: {}, // maps ua string to a ua object,
-  log: false
+  'ua': '',
+  'blacklist': [],
+  'whitelist': [],
+  'custom': {},
+  'siblings': {}, // a list of domains that are considered siblings (use same index for all)
+  'mode': 'blacklist',
+  'color': '#777',
+  'cache': true,
+  'exactMatch': false,
+  'protected': ['google.com/recaptcha', 'gstatic.com/recaptcha'],
+  'parser': {}, // maps ua string to a ua object,
+  'log': false,
+  'json-guid': 'na'
 };
 window.prefs = prefs; // access from popup
 
@@ -91,11 +89,29 @@ chrome.storage.local.get(prefs, ps => {
     // update prefs.ua from the managed storage
     try {
       chrome.storage.managed.get({
-        ua: ''
+        'ua': '',
+        'json': ''
       }, rps => {
-        if (!chrome.runtime.lastError && rps.ua) {
-          chrome.storage.local.set({
-            ua: rps.ua
+        if (!chrome.runtime.lastError) {
+          const p = {};
+          if (rps.json) {
+            try {
+              const j = JSON.parse(rps.json);
+              if (prefs['json-guid'] !== j['json-guid'] || j['json-forced']) {
+                Object.assign(p, j);
+                console.warn('preferences are updated by an admin');
+              }
+            }
+            catch (e) {
+              console.warn('cannot parse remote JSON', e);
+            }
+          }
+          if (rps.ua) {
+            p.ua = rps.ua;
+            console.warn('user-agent string is updated by an admin');
+          }
+          chrome.storage.local.set(p, () => {
+            ua.update(undefined, undefined, DCSI);
           });
         }
         else {
diff --git a/extension/data/options/index.css b/extension/data/options/index.css
index f4d56ce..890d673 100644
--- a/extension/data/options/index.css
+++ b/extension/data/options/index.css
@@ -101,3 +101,9 @@ textarea {
     grid-template-columns: 1fr 1fr;
   }
 }
+.admin {
+  background-color: #ffffed;
+  border: solid 1px #e8ec3a;
+  padding: 10px;
+  margin: 15px 0;
+}
diff --git a/extension/data/options/index.html b/extension/data/options/index.html
index 436290f..e327e13 100644
--- a/extension/data/options/index.html
+++ b/extension/data/options/index.html
@@ -60,12 +60,13 @@
     <h1>Sibling Hostnames</h1>
     <span id="toggle-sibling-desc">Description</span>
   </div>
-  <p for="toggle-sibling-desc" class="note hidden">A JSON array that contains one or more groups of hostnames to have a single user-agent string per group for the "Custom Mode". For all hostnames in one group, the user-agent string calculation only occurs once, and all the other members use the same calculated string. This is useful to make sure a group of connected websites only access to the same user-agent string. Press <a href="#" id="sample-3">here</a> to insert a sample JSON array.</p>
+  <p for="toggle-sibling-desc" class="note hidden">A JSON array that contains one or more groups of hostnames to have a single user-agent string per group. For all hostnames in one group, the user-agent string calculation only occurs once, and all the other members use the same calculated string. This is useful to make sure a group of connected websites only access to the same user-agent string. Press <a href="#" id="sample-3">here</a> to insert a sample JSON array.</p>
   <textarea id="siblings" rows="5" wrap="off"></textarea>
 
+  <div class="admin">This extension supports managed storage. All the preferences can be pre-configured by <a href="https://add0n.com/useragent-switcher.html#faq20">the domain administrator</a></div>
   <div id="backup">
     <button id="import">Import Settings</button>
-    <button id="export">Export Settings</button>
+    <button title="to generate minified version, press Shift key while pressing this button" id="export">Export Settings</button>
   </div>
   <div id="tools">
     <button id="help">FAQs Page (Help)</button>
diff --git a/extension/data/options/index.js b/extension/data/options/index.js
index 5ac02c9..3ee487c 100644
--- a/extension/data/options/index.js
+++ b/extension/data/options/index.js
@@ -24,6 +24,7 @@ function save() {
   catch (e) {
     window.setTimeout(() => {
       notify('Custom JSON error: ' + e.message, 5000);
+      alert('Custom JSON error: ' + e.message);
       document.getElementById('custom').value = c;
     }, 1000);
   }
@@ -36,6 +37,7 @@ function save() {
   catch (e) {
     window.setTimeout(() => {
       notify('Parser JSON error: ' + e.message, 5000);
+      alert('Parser JSON error: ' + e.message);
       document.getElementById('parser').value = p;
     }, 1000);
   }
@@ -52,11 +54,10 @@ function save() {
   catch (e) {
     window.setTimeout(() => {
       notify('Sibling JSON error: ' + e.message, 5000);
-      document.getElementById('siblings').value = c;
+      alert('Sibling JSON error: ' + e.message);
+      document.getElementById('siblings').value = s;
     }, 1000);
   }
-  console.log(siblings);
-
 
   chrome.storage.local.set({
     exactMatch: document.getElementById('exactMatch').checked,
@@ -90,10 +91,7 @@ function restore() {
     blacklist: [],
     custom: {},
     parser: {},
-    siblings: {
-      'www.google.com': 0,
-      'www.youtube.com': 0
-    },
+    siblings: {},
     protected: ['google.com/recaptcha', 'gstatic.com/recaptcha']
   }, prefs => {
     document.getElementById('exactMatch').checked = prefs.exactMatch;
@@ -178,9 +176,23 @@ document.getElementById('help').addEventListener('click', () => {
 });
 
 // export
-document.getElementById('export').addEventListener('click', () => {
+document.getElementById('export').addEventListener('click', e => {
+  const guid = 'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'.replace(/[xy]/g, c => {
+    const r = Math.random() * 16 | 0;
+    const v = c == 'x' ? r : (r & 0x3 | 0x8);
+    return v.toString(16);
+  });
+
   chrome.storage.local.get(null, prefs => {
-    const text = JSON.stringify(prefs, null, '  ');
+    for (const key of Object.keys(prefs)) {
+      if (key && key.startsWith('cache.')) {
+        delete prefs[key];
+      }
+    }
+    const text = JSON.stringify(Object.assign({}, prefs, {
+      'json-guid': guid,
+      'json-forced': false
+    }), null, e.shiftKey ? '' : '  ');
     const blob = new Blob([text], {type: 'application/json'});
     const objectURL = URL.createObjectURL(blob);
     Object.assign(document.createElement('a'), {
diff --git a/extension/manifest.json b/extension/manifest.json
index 24e5ac3..791e8b7 100755
--- a/extension/manifest.json
+++ b/extension/manifest.json
@@ -2,7 +2,7 @@
   "manifest_version": 2,
   "name": "User-Agent Switcher and Manager",
   "short_name": "useragent-switcher",
-  "version": "0.4.0.2",
+  "version": "0.4.1",
 
   "description": "Spoof websites trying to gather information about your web navigation to deliver distinct content you may not want",
 
diff --git a/extension/schema.json b/extension/schema.json
index 7a6a1da..96b767d 100644
--- a/extension/schema.json
+++ b/extension/schema.json
@@ -4,6 +4,10 @@
     "ua": {
       "title": "Custom User-Agent String",
       "type": "string"
+    },
+    "json": {
+      "title": "JSON String of all Preferences",
+      "type": "string"
     }
   }
 }