diff --git a/.eslintrc.yml b/.eslintrc.yml
index 8f75dacf6..79d68bc7f 100644
--- a/.eslintrc.yml
+++ b/.eslintrc.yml
@@ -6,7 +6,6 @@
     es6: true
     browser: true
     jquery: true
-    webextensions: true
   extends: eslint:recommended
   rules:
     dot-notation: [error, allowPattern: "^[A-Z]"]
@@ -72,3 +71,5 @@
     GM_openInTab: writable
     GM_listValues: writable
     GM_xmlhttpRequest: writable
+
+    bridge_call: writable
diff --git a/Extensions/xkit_patches.js b/Extensions/xkit_patches.js
index 97f736268..b8982e0b0 100644
--- a/Extensions/xkit_patches.js
+++ b/Extensions/xkit_patches.js
@@ -19,8 +19,7 @@ XKit.extensions.xkit_patches = new Object({
 		if (XKit.browser().firefox === true && XKit.storage.get("xkit_patches", "w_edition_warned") !== "true") {
 			let version = XKit.tools.parse_version(XKit.version);
 			if (version.major === 7 && version.minor >= 8) {
-				fetch(browser.runtime.getURL("manifest.json")) // eslint-disable-line no-undef
-					.then(response => response.json())
+				bridge_call("browser.runtime.getManifest")
 					.then(responseData => {
 						if (responseData.applications && responseData.applications.gecko.id === "@new-xkit-w" ||
 							responseData.browser_specific_settings && responseData.browser_specific_settings.gecko.id === "@new-xkit-w") {
diff --git a/background.js b/background.js
new file mode 100644
index 000000000..50219bd60
--- /dev/null
+++ b/background.js
@@ -0,0 +1,91 @@
+/* globals browser, chrome */
+
+if (typeof browser === "undefined") {
+	// eslint-disable-next-line no-global-assign
+	browser = chrome;
+}
+
+function isUserScriptsAvailable() {
+	try {
+		browser.userScripts;
+		return true;
+	} catch {
+		return false;
+	}
+}
+
+if (isUserScriptsAvailable) {
+	browser.userScripts.configureWorld({
+		csp: "script-src 'self' 'unsafe-inline' 'unsafe-eval'",
+		messaging: true,
+	});
+
+	browser.runtime.onInstalled.addListener(async () => {
+		const existingScripts = await browser.userScripts.getScripts({
+			ids: ["new-xkit"],
+		});
+		browser.userScripts[existingScripts.length > 0 ? "update" : "register"]([
+			{
+				id: "new-xkit",
+				// allFrames: true,
+				runAt: "document_start",
+				excludeMatches: [
+					"*://*.tumblr.com/*/audio_player_iframe/*",
+					"*://*.tumblr.com/*/photoset_iframe/*",
+					"*://assets.tumblr.com/*",
+					"*://*.media.tumblr.com/*",
+					"*://www.tumblr.com/upload/image*",
+					"*://www.tumblr.com/video/*",
+				],
+				matches: ["*://*.tumblr.com/*"],
+				js: [
+					"bridge.js",
+					"vendor/lodash.min.js",
+					"vendor/jquery.js",
+					"vendor/tiptip.js",
+					"vendor/moment.js",
+					"vendor/nano.js",
+					"xkit.js",
+				].map(file => ({file})),
+				world: "USER_SCRIPT",
+			},
+		]);
+	});
+}
+
+// must use synchronous callback form due to https://issues.chromium.org/issues/40753031
+browser.runtime.onUserScriptMessage.addListener((request, sender, sendResponse) => {
+	console.log("onUserScriptMessage", {request, sender, sendResponse});
+
+	if (request.func) {
+		(async () => {
+			const {func, args = []} = request;
+
+			switch (func) {
+				case "browser.runtime.getManifest":
+					sendResponse(await browser.runtime.getManifest(...args));
+					break;
+				case "browser.storage.local.get":
+					sendResponse(await browser.storage.local.get(...args));
+					break;
+				case "browser.storage.local.getBytesInUse":
+					sendResponse(await browser.storage.local.getBytesInUse(...args));
+					break;
+				case "browser.storage.local.remove":
+					sendResponse(await browser.storage.local.remove(...args));
+					break;
+				case "browser.storage.local.clear":
+					sendResponse(await browser.storage.local.clear(...args));
+					break;
+				case "browser.storage.local.set":
+					sendResponse(await browser.storage.local.set(...args));
+					break;
+				case "browser.runtime.getURL":
+					sendResponse(await browser.runtime.getURL(...args));
+					break;
+			}
+		})();
+	}
+
+	return true;
+});
diff --git a/bridge.js b/bridge.js
index 5596f1214..6a4b4cc18 100644
--- a/bridge.js
+++ b/bridge.js
@@ -8,7 +8,7 @@
 
 */
 
-/* globals msBrowser */
+/* globals browser, chrome, msBrowser */
 
 if (typeof(browser) === 'undefined') {
 	if (typeof(chrome) !== 'undefined') {
@@ -23,10 +23,12 @@ var bridge_error_object;
 var xkit_storage = {};
 var bridge_ver = "2.2.1";
 
+async function bridge_call(func, args) { // eslint-disable-line no-redeclare
+	return browser.runtime.sendMessage({ func, args });
+}
+
 try {
-	var storage = browser.storage.local;
 	var storage_loaded = false;
-	var framework_version = getVersion(); // eslint-disable-line no-redeclare
 	var storage_used = 0; // eslint-disable-line no-redeclare
 	var storage_max = -1; // eslint-disable-line no-redeclare
 	init_bridge();
@@ -49,17 +51,14 @@ function getBridgeError() { // eslint-disable-line no-redeclare
 	return m_object;
 }
 
-function getVersion() {
-	var xhr = new XMLHttpRequest();
-	xhr.open('GET', browser.runtime.getURL('manifest.json'), false);
-	xhr.send(null);
-	var manifest = JSON.parse(xhr.responseText);
+async function getVersion() {
+	const manifest = await bridge_call("browser.runtime.getManifest");
 	return manifest.version;
 }
 
-function call_xkit() {
+async function call_xkit() {
 	if (typeof XKit !== "undefined") {
-		XKit.init();
+		XKit.init(await getVersion());
 	} else {
 		setTimeout(function() { call_xkit(); }, 1);
 	}
@@ -74,7 +73,7 @@ function init_bridge() {
 
 	try {
 
-		storage.get(function(items) {
+		bridge_call("browser.storage.local.get").then(function(items) {
 
 			if (browser.runtime.lastError) {
 				last_error = browser.runtime.lastError.message;
@@ -107,15 +106,12 @@ function init_bridge() {
 			storage_loaded = true;
 			console.log("[XKit Bridge] Storage loaded, calling XKit.. bye!");
 
-			if (storage.getBytesInUse) {
-				storage.getBytesInUse(function(bytes) {
-					storage_used = bytes;
-					storage_max = -1;
-					call_xkit();
-				});
-			} else {
+			bridge_call("browser.storage.local.getBytesInUse").then(function(bytes) {
+				storage_used = bytes;
+				storage_max = -1;
 				call_xkit();
-			}
+			});
+
 
 		});
 
@@ -134,8 +130,8 @@ function init_bridge() {
 
 function GM_flushStorage(callback) { // eslint-disable-line no-redeclare
 
-	storage.remove("xkit_something", function() {
-		storage.clear(function(items) {
+	bridge_call("browser.storage.local.remove", ["xkit_something"]).then(function() {
+		bridge_call("browser.storage.local.clear").then(function(items) {
 			var last_error = 'unknown error';
 			if (browser.runtime.lastError) {
 				last_error = browser.runtime.lastError.message;
@@ -149,11 +145,11 @@ function GM_flushStorage(callback) { // eslint-disable-line no-redeclare
 
 function GM_deleteAllValues(callback) { // eslint-disable-line no-redeclare
 
-	storage.get(function(items) {
+	bridge_call("browser.storage.local.get").then(function(items) {
 		for (var key in items) {
 			GM_deleteValue(key);
 		}
-		storage.clear();
+		bridge_call("browser.storage.local.clear");
 		callback();
 	});
 
@@ -176,7 +172,7 @@ function GM_getValue(name, defaultValue) { // eslint-disable-line no-redeclare
 function GM_deleteValue(name) { // eslint-disable-line no-redeclare
 
 	//console.log("Bridge : GM_deleteValue for " + name);
-	storage.remove(name);
+	bridge_call("browser.storage.local.remove", [name]);
 	delete xkit_storage[name];
 
 }
@@ -187,7 +183,7 @@ function GM_setValue(name, value) { // eslint-disable-line no-redeclare
 	var m_name = name;
 	m_object[ m_name ] = value;
 	xkit_storage[name] = value;
-	storage.set(m_object);
+	bridge_call("browser.storage.local.set", [m_object]);
 	return true;
 
 }
diff --git a/manifest.json b/manifest.json
index 5fea89873..26b2b1f24 100644
--- a/manifest.json
+++ b/manifest.json
@@ -11,29 +11,29 @@
       "*://www.tumblr.com/upload/image*",
       "*://www.tumblr.com/video/*"
     ],
-    "js": [
-      "bridge.js",
-      "vendor/lodash.min.js",
-      "vendor/jquery.js",
-      "vendor/tiptip.js",
-      "vendor/moment.js",
-      "vendor/nano.js",
-      "xkit.js"
-    ],
     "matches": [ "*://*.tumblr.com/*" ]
   } ],
+  "background": {
+    "scripts": [ "background.js" ],
+    "service_worker": "background.js",
+    "persistent": false
+  },
   "description": "A fork of XKit, the extension framework for Tumblr.",
   "homepage_url": "https://github.com/new-xkit/XKit",
   "icons": {
     "128": "icon.png"
   },
-  "manifest_version": 2,
-  "minimum_chrome_version": "88.0",
+  "manifest_version": 3,
+  "minimum_chrome_version": "120.0",
   "name": "New XKit",
   "author": "New XKit Team",
-  "permissions": ["storage", "unlimitedStorage", "*://*.tumblr.com/*", "https://new-xkit.github.io/XKit/*", "https://cloud.new-xkit.com/*" ],
+  "permissions": ["storage", "unlimitedStorage", "userScripts" ],
+  "host_permissions": [ "*://*.tumblr.com/*", "https://new-xkit.github.io/XKit/*", "https://cloud.new-xkit.com/*" ],
   "version": "7.10.0",
-  "web_accessible_resources": [ "*.js", "*.json", "*.css" ],
+  "web_accessible_resources": [{
+    "resources": [ "*.js", "*.json", "*.css" ],
+    "matches": [ "*://www.tumblr.com/*" ]
+  }],
   "browser_specific_settings": {
     "gecko": {
       "id": "@new-xkit",
diff --git a/xkit.js b/xkit.js
index 326f2fdd7..1d94334a7 100755
--- a/xkit.js
+++ b/xkit.js
@@ -6,7 +6,7 @@ var xkit_global_start = Date.now();  // log start timestamp
 	if (typeof XKit !== "undefined") { return; }
 
 	XKit = {
-		version: framework_version,
+		version: undefined,
 		api_key: "kZSI0VnPBJom8cpIeTFw4huEh9gGbq4KfWKY7z5QECutAAki6D",
 		page: {
 			standard:
@@ -23,7 +23,8 @@ var xkit_global_start = Date.now();  // log start timestamp
 			xkit:
 				document.location.href.indexOf('://www.tumblr.com/xkit_') !== -1
 		},
-		init: function() {
+		init: function(version) {
+			XKit.version = version;
 			if (!XKit.page.xkit) {
 				XKit.init_flags();
 			}
@@ -3328,13 +3329,13 @@ function show_message(title, msg, icon, buttons) {
 	});
 }
 
-function xkit_init_special() {
+async function xkit_init_special() {
 
 	$("body").html("");
 	document.title = "XKit";
 
 	XKit.notifications.init();
-	XKit.notifications.add("<b>Welcome to XKit " + framework_version + "</b><br/>&copy; 2011-2013 STUDIOXENIX");
+	XKit.notifications.add("<b>Welcome to XKit " + XKit.version + "</b><br/>&copy; 2011-2013 STUDIOXENIX");
 
 	if (document.location.href.indexOf("/xkit_reset") !== -1) {
 		XKit.special.reset();
@@ -3354,11 +3355,8 @@ function xkit_init_special() {
 
 	if (document.location.href.indexOf("/xkit_editor") !== -1) {
 		if (typeof(browser) !== 'undefined') {
-			var xhr = new XMLHttpRequest();
-			xhr.open('GET', browser.extension.getURL('editor.js'), false);
-			xhr.send(null);
 			try {
-				new Function(xhr.responseText + "\n//# sourceURL=xkit/editor.js")();
+				await import(await bridge_call("browser.runtime.getURL", ["/editor.js"]));
 				XKit.extensions.xkit_editor.run();
 			} catch (e) {
 				XKit.window.show("Can't launch XKit Editor", "<p>" + e.message + "</p>", "error", "<div id=\"xkit-close-message\" class=\"xkit-button default\">OK</div>");
@@ -3536,7 +3534,7 @@ function install_extension(mdata, callback) {
 
 function xkit_install() {
 
-	XKit.window.show("Welcome to New XKit " + framework_version + "!", "<b>Please wait while I initialize the setup. This might take a while.<br/>Please do not navigate away from this page.</b>", "info");
+	XKit.window.show("Welcome to New XKit " + XKit.version + "!", "<b>Please wait while I initialize the setup. This might take a while.<br/>Please do not navigate away from this page.</b>", "info");
 	console.log("Trying to retrieve XKit Installer.");
 
 	XKit.install("xkit_installer", function(mdata) {
@@ -3612,7 +3610,7 @@ function show_error_update(message) {
  * Functions used in place of gulp build server
  */
 
-const loadFile = path => fetch(browser.runtime.getURL(path)).then(response => response.text());
+const loadFile = async path => fetch(await bridge_call("browser.runtime.getURL", [path])).then(response => response.text());
 
 const extensionDataCache = {};