Privacy

Last updated 7 October 2026

Sapling is a language learning site at mysapl.ing, with a browser extension, Sapling Subtitles, for learning from YouTube. This page explains what each keeps and where it goes. There are no ads, no analytics and no tracking, and nothing is sold.

Your account

Signing up stores your email address and a password (kept only as a secure hash) with Supabase, the database Sapling runs on. Your learning progress on the islands and the words in your Notebook are stored there too, tied to your account and visible only to you.

The Sapling Subtitles extension

• What it reads. It runs only on youtube.com. When a video has subtitles in a language you chose to learn, it keeps a copy of the subtitle file YouTube's player downloads. It does not read your YouTube account, history, comments or anything else on the page.
• What it sends. To show what each word means, it sends the subtitle lines near where you're watching, with the video's title, to Sapling's server. The server asks Google's Gemini AI to annotate them and sends the answer back. Annotated lines are kept in a shared cache, without anything that identifies you, so the next person watching the same video gets them straight away.
• What it saves. When you click a word, it saves the word, its meaning, the sentence it came from and the video's ID, title and timestamp to your Notebook, so you can review it and jump back to that moment.
• Your sign-in. The extension uses your mysapl.ing sign-in cookie to talk to Sapling as you. It never sees your password.
• On your computer. Your settings, a copy of your saved words and recent annotations are kept in the extension's own storage in your browser, so rewatching a video doesn't ask again.

Who else handles it

• Supabase stores accounts, progress and Notebooks.
• Vercel hosts the site and its server.
• Google (Gemini) annotates subtitle lines and helps with a few features on the islands. It receives text, not your account.

Deleting things

You can remove any word from your Notebook at any time. Removing the extension deletes everything it stored in your browser. To delete your account and everything tied to it, write to the contact address on Sapling Subtitles' Chrome Web Store page and it will be done within 30 days.