diff --git a/apps/chrome-extension/e2e/overlay-ui.spec.ts b/apps/chrome-extension/e2e/overlay-ui.spec.ts
index dc4a287ee86..38b10d17d0e 100644
--- a/apps/chrome-extension/e2e/overlay-ui.spec.ts
+++ b/apps/chrome-extension/e2e/overlay-ui.spec.ts
@@ -346,9 +346,7 @@ test("clicking X in the panel closes the panel and the camera preview", async ()
 
 		const panelFrame = frameWithUrl(targetPage, "popup.html");
 		if (!panelFrame) throw new Error("panel frame missing");
-		await panelFrame
-			.locator('button[aria-label="Close Cap and hide all recorder UI"]')
-			.click();
+		await panelFrame.getByTestId("close-recorder-ui").click();
 
 		// The panel and the camera preview should both tear down.
 		await expect
@@ -419,7 +417,7 @@ test("a failed recording start reopens the panel with the error", async () => {
 			.toBe(true);
 		const panelFrame = frameWithUrl(targetPage, "popup.html");
 		if (!panelFrame) throw new Error("panel frame missing");
-		await expect(panelFrame.getByText("Recording failed.")).toBeVisible({
+		await expect(panelFrame.getByTestId("recording-start-error")).toBeVisible({
 			timeout: 10_000,
 		});
 		await targetPage.screenshot({
diff --git a/apps/chrome-extension/public/_locales/en/messages.json b/apps/chrome-extension/public/_locales/en/messages.json
new file mode 100644
index 00000000000..9534de3b6d5
--- /dev/null
+++ b/apps/chrome-extension/public/_locales/en/messages.json
@@ -0,0 +1,17 @@
+{
+	"actionDefaultTitle": {
+		"message": "Record your screen with Cap"
+	},
+	"extensionDescription": {
+		"message": "Free, open source screen recorder. Capture your screen, tab, camera & mic in Chrome and share a video link the moment you stop."
+	},
+	"extensionName": {
+		"message": "Cap - Screen Recorder & Screen Capture"
+	},
+	"extensionShortName": {
+		"message": "Cap"
+	},
+	"offscreenJustification": {
+		"message": "Record and upload Cap videos from an extension page."
+	}
+}
diff --git a/apps/chrome-extension/public/_locales/zh_CN/messages.json b/apps/chrome-extension/public/_locales/zh_CN/messages.json
new file mode 100644
index 00000000000..52a44647182
--- /dev/null
+++ b/apps/chrome-extension/public/_locales/zh_CN/messages.json
@@ -0,0 +1,17 @@
+{
+	"actionDefaultTitle": {
+		"message": "使用 Cap 录制屏幕"
+	},
+	"extensionDescription": {
+		"message": "免费开源的屏幕录制工具。在 Chrome 中录制屏幕、标签页、摄像头和麦克风，停止录制后即可分享视频链接。"
+	},
+	"extensionName": {
+		"message": "Cap - 屏幕录制与截图"
+	},
+	"extensionShortName": {
+		"message": "Cap"
+	},
+	"offscreenJustification": {
+		"message": "从扩展页面录制并上传 Cap 视频。"
+	}
+}
diff --git a/apps/chrome-extension/public/manifest.json b/apps/chrome-extension/public/manifest.json
index eeb058f457c..3a6b6a850fc 100644
--- a/apps/chrome-extension/public/manifest.json
+++ b/apps/chrome-extension/public/manifest.json
@@ -1,8 +1,9 @@
 {
 	"manifest_version": 3,
-	"name": "Cap - Screen Recorder & Screen Capture",
-	"short_name": "Cap",
-	"description": "Free, open source screen recorder. Capture your screen, tab, camera & mic in Chrome and share a video link the moment you stop.",
+	"name": "__MSG_extensionName__",
+	"short_name": "__MSG_extensionShortName__",
+	"description": "__MSG_extensionDescription__",
+	"default_locale": "en",
 	"version": "1.0.2",
 	"homepage_url": "https://cap.so",
 	"minimum_chrome_version": "116",
@@ -13,7 +14,7 @@
 		"128": "icons/icon-128.png"
 	},
 	"action": {
-		"default_title": "Record your screen with Cap",
+		"default_title": "__MSG_actionDefaultTitle__",
 		"default_icon": {
 			"16": "icons/icon-16.png",
 			"32": "icons/icon-32.png",
diff --git a/apps/chrome-extension/src/background/service-worker.ts b/apps/chrome-extension/src/background/service-worker.ts
index 43eccb06c54..7133794f03e 100644
--- a/apps/chrome-extension/src/background/service-worker.ts
+++ b/apps/chrome-extension/src/background/service-worker.ts
@@ -5,6 +5,7 @@ import {
 	parseAuthResponse,
 	revokeAuth,
 } from "../shared/api";
+import { msg } from "../shared/i18n";
 import {
 	isRecordingStatusBroadcast,
 	isServiceWorkerRequest,
@@ -219,7 +220,7 @@ const createOffscreenDocument = () =>
 			{
 				url: OFFSCREEN_URL,
 				reasons: ["USER_MEDIA", "DISPLAY_MEDIA", "BLOBS", "AUDIO_PLAYBACK"],
-				justification: "Record and upload Cap videos from an extension page.",
+				justification: msg("offscreenJustification"),
 			},
 			() => {
 				const error = chrome.runtime.lastError;
diff --git a/apps/chrome-extension/src/popup/components/recorder-header.tsx b/apps/chrome-extension/src/popup/components/recorder-header.tsx
index 3b6d92e130c..8b2294c114e 100644
--- a/apps/chrome-extension/src/popup/components/recorder-header.tsx
+++ b/apps/chrome-extension/src/popup/components/recorder-header.tsx
@@ -42,6 +42,7 @@ export const RecorderHeader = ({
 							: "cursor-pointer transition-transform hover:scale-110",
 					)}
 					aria-label="Close Cap and hide all recorder UI"
+					data-testid="close-recorder-ui"
 				>
 					<X
 						size={10}
diff --git a/apps/chrome-extension/src/popup/main.tsx b/apps/chrome-extension/src/popup/main.tsx
index be8fc9c0469..3eb2f9139de 100644
--- a/apps/chrome-extension/src/popup/main.tsx
+++ b/apps/chrome-extension/src/popup/main.tsx
@@ -699,7 +699,10 @@ function App() {
 							</div>
 						)}
 						{status.phase === "error" && (
-							<div className="cap-fade-up rounded-md border border-red-6 bg-red-3/70 px-3 py-2 text-xs leading-snug text-red-12">
+							<div
+								className="cap-fade-up rounded-md border border-red-6 bg-red-3/70 px-3 py-2 text-xs leading-snug text-red-12"
+								data-testid="recording-start-error"
+							>
 								<span className="font-medium">Recording failed.</span>{" "}
 								{status.message}
 							</div>
diff --git a/apps/chrome-extension/src/shared/i18n.test.ts b/apps/chrome-extension/src/shared/i18n.test.ts
new file mode 100644
index 00000000000..54c20b985dc
--- /dev/null
+++ b/apps/chrome-extension/src/shared/i18n.test.ts
@@ -0,0 +1,71 @@
+import { afterEach, describe, expect, it, vi } from "vitest";
+import englishMessages from "../../public/_locales/en/messages.json";
+import chineseMessages from "../../public/_locales/zh_CN/messages.json";
+import { type MessageKey, msg } from "./i18n";
+
+afterEach(() => {
+	vi.unstubAllGlobals();
+});
+
+describe("extension messages", () => {
+	it("keeps locale catalogs aligned", () => {
+		expect(Object.keys(chineseMessages).sort()).toEqual(
+			Object.keys(englishMessages).sort(),
+		);
+	});
+
+	it("uses the browser locale when a translation is available", () => {
+		const getMessage = vi.fn(() => "使用 Cap 录制屏幕");
+		vi.stubGlobal("chrome", { i18n: { getMessage } });
+
+		expect(msg("actionDefaultTitle")).toBe("使用 Cap 录制屏幕");
+		expect(getMessage).toHaveBeenCalledWith("actionDefaultTitle", undefined);
+	});
+
+	it("falls back to English outside an extension context", () => {
+		vi.stubGlobal("chrome", undefined);
+
+		expect(msg("actionDefaultTitle")).toBe("Record your screen with Cap");
+	});
+
+	it("falls back to English when Chrome i18n is unavailable", () => {
+		vi.stubGlobal("chrome", {});
+
+		expect(msg("actionDefaultTitle")).toBe("Record your screen with Cap");
+	});
+
+	it("falls back to English when Chrome cannot resolve a message", () => {
+		vi.stubGlobal("chrome", {
+			i18n: { getMessage: vi.fn(() => "") },
+		});
+
+		expect(msg("offscreenJustification")).toBe(
+			"Record and upload Cap videos from an extension page.",
+		);
+	});
+
+	it("applies substitutions to the English fallback", () => {
+		const originalMessage = englishMessages.actionDefaultTitle.message;
+		vi.stubGlobal("chrome", undefined);
+
+		try {
+			englishMessages.actionDefaultTitle.message = "Record $1";
+			expect(msg("actionDefaultTitle", "your screen")).toBe(
+				"Record your screen",
+			);
+
+			englishMessages.actionDefaultTitle.message = "Record $1 with $2";
+			expect(msg("actionDefaultTitle", ["your screen", "Cap"])).toBe(
+				"Record your screen with Cap",
+			);
+		} finally {
+			englishMessages.actionDefaultTitle.message = originalMessage;
+		}
+	});
+
+	it("returns the key when the English fallback is missing", () => {
+		vi.stubGlobal("chrome", undefined);
+
+		expect(msg("missingMessage" as MessageKey)).toBe("missingMessage");
+	});
+});
diff --git a/apps/chrome-extension/src/shared/i18n.ts b/apps/chrome-extension/src/shared/i18n.ts
new file mode 100644
index 00000000000..7bff04c1ca6
--- /dev/null
+++ b/apps/chrome-extension/src/shared/i18n.ts
@@ -0,0 +1,22 @@
+import englishMessages from "../../public/_locales/en/messages.json";
+
+export type MessageKey = keyof typeof englishMessages & string;
+
+export const msg = (key: MessageKey, substitutions?: string | string[]) => {
+	const localizedMessage =
+		typeof chrome === "undefined" ||
+		typeof chrome.i18n?.getMessage !== "function"
+			? ""
+			: chrome.i18n.getMessage(key, substitutions);
+
+	if (localizedMessage) return localizedMessage;
+
+	const fallback = englishMessages[key]?.message || key;
+	if (!substitutions) return fallback;
+
+	const values = Array.isArray(substitutions) ? substitutions : [substitutions];
+	return fallback.replace(
+		/\$(\d+)/g,
+		(_match, index: string) => values[Number(index) - 1] ?? "",
+	);
+};