Chrome extension privacy policy

Bilingual Mix — Interleaved Audio Maker · effective 2026-10-22

Short version: the extension sends the two audio files you choose to bilingualmix.com only to transcribe them and pair the lines. It does not send anything else, it does not read the pages you browse, it contains no analytics or advertising code, and the finished MP3 is assembled on your own device and never uploaded.

What the extension sends

The two audio files you select. They are posted over HTTPS to https://bilingualmix.com/api/align so that speech recognition can produce sentence timestamps and the sentence pairs can be matched across the two languages.
Your language choices and options for that request (which language each track is, and the two durations your browser reports), so the server can enforce its free quota before spending transcription cost.

That is the complete list. Without an account, nothing identifies you beyond what any web request carries (IP address, user agent), and that is what the free-tier counter uses.

If you connect a website account (optional)

You can use the extension without an account forever. Connecting one only changes which quota the runs are charged to: the same account quota you use on the website, instead of the anonymous per-IP allowance.

What is stored on your device: an access token (a signed string that names your email and an expiry date) and your email address, in chrome.storage.local.
What is sent with a request: that token in the Authorization header of the /api/align call. Our server verifies the signature, looks up the account, and counts the run against it. No cookie is read, and no other page is touched.
How it gets there: the token is issued once, on bilingualmix.com, to a browser that is already signed in — after you press Connect this browser. It is handed to the extension through a one-time code that expires in 10 minutes and can only be redeemed by the extension that requested it.
How to revoke it: press Disconnect in the extension. The token is deleted locally. The token also stops working 120 days after it was issued, and you can ask us to cut it off earlier by email.

Connecting an account does not give us anything new: we already have your email from sign-up. It does not grant access to your browsing history, other tabs, or the pages you visit.

Where it goes

To run the transcription, the uploaded audio is passed from our API to our speech-recognition provider (Groq, Inc., United States). The resulting transcript text is sent to Cloudflare Workers AI to compute cross-language semantic similarity and build the pairs. Our own servers do not keep your audio files or the transcripts. These providers process data under their own privacy policies. We do not sell, rent, or share this data with anyone else.

What stays on your device

Cutting, joining and MP3 encoding run locally in the extension page through WebAssembly (LAME). The finished track is created in your browser's memory and is only written to disk if you click Download.
Your preferences (interface language, pause and padding values, track order) are stored with chrome.storage.local so the form is pre-filled next time. Nothing in that storage is transmitted.
Nothing else. Files, transcripts and settings are discarded when you close the tab.

What the extension does not do

It does not read, modify or inject anything into the web pages you visit. It has no content scripts and no access to any site other than bilingualmix.com.
It does not include analytics, tracking pixels, advertising, or remote code. All scripts ship inside the package.
It does not use tracking cookies and does not read your sign-in cookie. Unless you connect an account, a request carries no account identifier at all; if you do connect one, it uses the token described above and nothing else.

Permissions, and why

Permission	Why it is needed
`storage`	Remembers your interface language and listening options locally.
`https://bilingualmix.com/*`	The only host the extension talks to: the alignment API and nothing else.

Retention

Audio and transcripts: not retained by us; they are processed for the request only.
Anonymous usage counters (processing minutes per IP per day, to enforce the free tier): kept for two days, then expire automatically.
Usage that was charged to a connected account is recorded against that account — the same daily / monthly rows the website uses — and stays for as long as the account exists.
Hosting logs: retained under Cloudflare's defaults for security purposes.

Children

The extension is a utility for adults preparing their own listening material. It is not directed at children under 13 and we do not knowingly collect data about them.

Changes and contact

Material changes will be posted on this page with a new effective date. Questions, or a request to delete usage data associated with your IP address: support@bilingualmix.com. We reply within 30 days.

中文说明

简述：扩展只会把你选中的两个音频文件发到 bilingualmix.com，用途只有两个——转写成带时间码的文字、把两种语言的句子配成对。除此之外不上传任何东西；不读取你浏览的网页；代码里没有统计、广告或远程脚本；成品 MP3 在本机切割合成，不会上传。

会上传：你选的两段音频、两条语言选择、两个时长（用于在花转写成本之前判断免费额度）。
去向：音频交给 Groq（美国）做语音识别，转写文本交给 Cloudflare Workers AI 做跨语言配对。我们自己的服务器不保存音频和转写文本；不出售、不出租、不共享给其他方。
留在本机：切割、拼接、MP3 编码全部走 WebAssembly 在扩展页面里完成，只有你点「下载」才会落盘；界面语言和停顿参数存在 chrome.storage.local，不对外发送。
权限：storage 用来记住设置；https://bilingualmix.com/* 是唯一会访问的站点。没有 content script，没有 tabs/downloads/cookies 之类多余权限。
可选：连接账号。不连接也能一直免费用。连接只是把额度从「按 IP 的匿名额度」换成「你账号那份额度」：本机 chrome.storage.local 存一枚签名令牌和你的邮箱，请求时放在 Authorization 头里；不读 cookie，不碰别的网页。令牌只能在已登录的网站上点「连接这个浏览器」时签发一次，交接码 10 分钟过期且只有发起请求的那个扩展能兑换；在扩展里点「断开」即删除，令牌也会在 120 天后自动失效。
保留：音频与转写不留存；按 IP 的每日分钟数计数保留两天后自动过期；托管平台日志按 Cloudflare 默认策略保留。
联系：support@bilingualmix.com