diff --git a/src/common/mainWorldI18n/Client.js b/src/common/mainWorldI18n/Client.js
new file mode 100644
index 0000000..b1b8286
--- /dev/null
+++ b/src/common/mainWorldI18n/Client.js
@@ -0,0 +1,20 @@
+import MainWorldContentScriptBridgeClient from '../mainWorldContentScriptBridge/Client.js';
+
+import {kCSTarget, kMWTarget} from './consts.js';
+
+// Main World i18n client (used in scripts injected into the Main World (MW) to
+// use the chrome.i18n API).
+export default class MWI18nClient extends MainWorldContentScriptBridgeClient {
+  constructor(timeout) {
+    super(kCSTarget, kMWTarget, timeout);
+  }
+
+  async getMessage(messageName, substitutions, options) {
+    return this._sendRequest(
+        'getMessage', {messageName, substitutions, options});
+  }
+
+  async getUILanguage() {
+    return this._sendRequest('getUILanguage', {});
+  }
+}