Privacy Policy
Updated 7 November 2026
Couplet is a browser extension that adds two lines of subtitles to YouTube videos, explains words, and helps you review the ones you save. This page says what it collects, why, and who else sees it.
In short
- We don't sell your data, show ads, or use it to track you.
- We collect only what the features below need.
- You can delete any word, or ask us to delete everything.
What we collect
| Data | Why | Where it goes |
|---|---|---|
| Your Google account's email address, name, and picture, when you sign in | To identify your account | Supabase |
| Words you save, with their sentences, translations, and the video's title and ID | To show and review them, on any computer you sign in on | Your device, then Supabase |
| Your review history | To schedule reviews and show progress | Your device, then Supabase |
| Words you look up, with the two languages involved | To explain the word. Your account or a random install ID guards against automated abuse | Cloudflare, then Alibaba Cloud |
| Subtitle lines around a word, when you choose Explain with AI | To explain the word in that sentence. Your account counts the daily limit, and isn't sent to the AI service | Cloudflare, then Alibaba Cloud |
| A hash of your network address, for signed-out lookups | To stop automated abuse. We don't store the address itself, and the count is removed within two days | Cloudflare |
| Subtitle lines from videos you watch with the extension on | To translate them | Google Translate |
We don't collect your watch history. A video's title and ID are stored only for videos you save a word from. Settings stay on your device.
Who else handles it
- Supabase stores your account, words, and reviews.
- Cloudflare runs our lookup service and this website.
- Alibaba Cloud is a China-based company whose AI service writes dictionary entries and explanations. We use its international service in Singapore. For a lookup, it receives the word and languages. For Explain with AI, it also receives up to three subtitle lines. It never receives your account or email.
- Google provides sign-in and translates subtitle lines.
Each handles the data under its own privacy policy.
Google user data
We use your Google account only to sign you in. We read your email address, name, and picture, and nothing else in your account. Our use of this information follows the Google API Services User Data Policy, including its Limited Use requirements. We don't share it for advertising or use it to train AI models.
How long we keep it
- Your account and words stay until you delete them.
- Deleting a word removes its content and reviews from the cloud. A small record that it was deleted stays, so your other devices can delete it too.
- Signing out or removing the extension doesn't delete your account. Words already synced come back when you sign in again.
- Dictionary entries and explanations are kept in a shared cache with no link to who asked.
Your choices
- Use subtitles and lookups without an account.
- Delete words, or export your list as a CSV, from the Dashboard.
- Ask us to delete your account and everything in it, at support@coupletapp.com.
Children
Couplet isn't directed at children under 13.
Changes
If this policy changes, we'll update this page and its date.