How the Immersion Atlas website and browser extension handle data.
Immersion Atlas is a free tool for building Japanese study decks from YouTube channels. All of it works without an account — nothing below changes unless you choose to sign in (see “If you sign in”).
When you start mining a channel on immersionatlas.com, the Immersion Atlas browser extension fetches the caption/transcript text of the videos you choose, using your own internet connection, and returns that text to immersionatlas.com. The extension does not read your YouTube account or your YouTube watch history, and it observes no browsing activity — with one exception you control: the optional immersion tracking described below, which is off by default.
If you choose “Connect Anki”, the extension connects only to the AnkiConnect add-on running on your own computer. After you approve access inside Anki, it finds cards with review intervals of at least 21 days and returns only the deduplicated Japanese headwords needed for your Immersion Atlas vocabulary profile. Full card fronts and backs, example sentences, media, review history, and AnkiWeb credentials are not sent to immersionatlas.com.
The extracted headwords are stored in your browser like any other known-word list. They stay on the device while signed out; if you choose to sign in, known words are included in the optional account backup described below. Automatic refresh happens only when the Immersion Atlas extension, desktop Anki, and AnkiConnect are available.
If you switch on “Track immersion on YouTube” in the extension's popup, the extension measures how many minutes of video you watch — but only on YouTube watch pages and in immersionatlas.com's own embedded players, and only for creators that are in the Immersion Atlas catalog. Videos by other creators, YouTube search, comments, recommendations, and all other browsing are never recorded.
This data stays on your device unless you sign in — signed out it is stored inside the extension (your browser's local extension storage) and is never transmitted to the Immersion Atlas server or anyone else; the immersion stats on immersionatlas.com/me.html read it directly from the extension in your browser. If you sign in, it is additionally backed up to your account so your other devices can show it (see “If you sign in”). You can export it as a file, delete it at any time from the extension popup (“Clear immersion data”), or remove it entirely by uninstalling the extension.
Fetched transcripts (public YouTube captions) are cached on the Immersion Atlas server so other users mining the same channel get them instantly. We do not collect names, emails, IP-based profiles, or any personally identifiable information.
You can optionally sign in with Google to back up your Immersion Atlas data and sync it across devices. Signing in is never required — every feature works without it, and signed-out users send us nothing personal at all.
If you do sign in, we store exactly this, on our own server in the EU (Hetzner, Germany): your email address from Google (used only to identify your account, contact you about it if ever needed, and delete it on request — we receive no other Google data, no watch history, no YouTube account access), and the study data you sync — your known words, level, interests, saved channels, comprehension progress, streak, and (if you use the extension's tracking) your immersion watch history.
These payloads exist only to give them back to you on your devices. We never analyze them, build profiles from them, share them, or use them for anything else. Deleting your account (the button on your page, or an email to us) permanently removes the account and every synced copy from our server; the data on your devices is yours and stays untouched.
To see whether Immersion Atlas is useful, we keep anonymous, aggregate counts of actions — e.g. “a deck was built” or “a transcript was fetched.” These are simple daily tallies with no names, IP addresses, cookies, or any identifier; they can't be traced back to you or a specific device.
We do not sell or share your data, show ads, or track you across sites. There are no third-party processors beyond Google's sign-in itself.
Last updated: 2026-08-10