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Palimpsest browser extension: privacy
Last updated 23 October 2026. This page covers the Palimpsest browser extension. The Palimpsest Privacy Notice covers your Palimpsest account and the rest of the service.
In short. The extension helps you learn a language on the web: it colours the words of the language you are learning by how well you know them, opens Palimpsest's word popup and flashcards, and shows a captions panel on YouTube. To decide which words a page contains, it reads the page on your computer. What it sends to Palimpsest is words (mostly their dictionary forms), not pages: never the address of a page you read or its text, unless you press Save to Palimpsest on it, or highlight a few words and add them to your flashcards (then only those words). We do not sell your data, share it for advertising, or use it for anything except your learning in Palimpsest.
It works for the languages on your Palimpsest account: Russian, Spanish, French, German, and the languages in early access. Russian is resolved partly by a dictionary inside the extension and partly by our server; the other languages are resolved entirely from a word list ("pack") the extension downloads from your account, so no page in those languages is sent for processing while you read.
What happens on your computer only
- Language check. On each page the extension checks, in your browser, whether the page is in one of the languages on your account. For any other page, it stops there, and nothing about it is sent or saved.
- Dictionary forms. On a Russian page, it works out each word's dictionary form with a dictionary that ships inside the extension (about 98% of words on a typical page). On a page in another of your languages, it uses the word pack downloaded for that language (see below); words the pack does not know yet are coloured as new until a later pack knows them.
- How you read. It notes, in your browser, how long each word was on your screen while you were active, how often it came into view, the reading pace of its paragraph, and how close it was to a word you looked up. Only these per-word summaries are ever sent (see below), never the timings themselves, scroll positions or clicks.
- Stored in your browser: your extension token, a copy of your word scores (with where each one came from and the day it last changed) and due flashcards (refreshed every 6 hours), the word packs for your non-Russian languages, your extension settings, reading events and word forms waiting to be sent, and a list of the pages in your languages you visited recently (site name and word counts only, shown in the extension's menu). Pages in other languages are not kept.
What is sent to Palimpsest, and why
Everything below goes only to Palimpsest's own server (palimpsest.tech), encrypted in transit.
| When | What is sent | Why, and what is kept |
|---|---|---|
| A Russian page has words the built-in dictionary does not know (about 1–2 in 100) | Those word forms, shuffled so they are not in page order, without your token. Words that look like names are never sent. | To find their dictionary forms. Not stored. |
| You connect your Palimpsest account (by pasting a token you create in Settings) | Your token, with the requests below. | So the extension acts for your account. Disconnecting in the extension revokes the token; you can also revoke it in Settings. |
| Every 6 hours, while connected | A request for your word scores, due flashcards and relevant settings, and, for each non-Russian language on your account, for its word pack (the dictionary forms of words, with general difficulty scores adjusted to your level). | They are downloaded to your browser. |
| Every couple of hours, after reading pages in a non-Russian language | The word forms from those pages that the pack did not know, shuffled, mixed across pages, and without your token. Words that look like names are never sent. | Our nightly job finds their dictionary forms and adds them to the next pack. The forms are deleted once processed. |
| Colouring a Russian page, while connected | The word forms on the page that your downloaded scores do not cover, shuffled and in batches. (Pages in your other languages are coloured from the pack and send nothing for this.) | So the server can score them exactly as the app does. Not stored. |
| You click a word, look it up, change its score, reject it, flag it for a deck or correct its dictionary form | The word's dictionary form, and your action. For a correction, the word as written and the form you chose. | Recorded in your account as the app records it. A correction enough learners share is shown to other learners as the word's reading, as a count, never with who chose it. To write a definition, the word (not the page) is sent to our AI provider, Anthropic. |
| You highlight words and choose Add to Palimpsest flashcards | The highlighted words (up to 12), to suggest their dictionary form, and then the card front you settle on. Never the sentence around them, the page or its address. | Kept as a flashcard candidate in your account, for a deck you make later. |
| You review a flashcard that popped up on a page | The card and your answer. | Saved as a review in your account. |
| You read without looking words up (on by default; can be switched off in Palimpsest Settings) | The dictionary forms of words you had on screen, and did not look up, with how often they appeared, the day, and the per-word summaries described above. On YouTube: the words of caption lines that played. | They count towards your word scores, as reading in the app does. They are sent in batches mixed across pages, so no batch is one page, and they never include the page, its address or the time of day. For your non-Russian languages they wait a little longer (a couple of hours) and are recorded by our nightly job. |
| You press Save to Palimpsest | That one page's address, title and text, or, for a YouTube video, its video id, title, channel and captions. | Saved to your Palimpsest library, so you can read or watch it in the app. Only on your press, only that page. |
What is never sent
- Your browsing history, and the address or text of any page you did not save.
- Anything from pages that are not in one of the languages on your account.
- Keystrokes, form contents, passwords, screenshots, audio or your location.
YouTube
On a YouTube video with captions in one of your languages, the extension reads the captions file that YouTube's own player downloads, and shows it in a panel beside the video. The captions stay in your browser. The words heard are counted as described above, and the video id and captions leave your browser only if you save the video.
Your choices
- Pause (in the extension's menu) stops everything: no reading, colouring, lookups or sending.
- Stop counting your reading but keep colours and lookups: Palimpsest → Settings → Browser extension.
- Disconnect revokes the token and deletes everything the extension downloaded from your browser. Removing the extension deletes all of its local data.
- To see or delete what is stored in your account, use the contact details and requests in the Palimpsest Privacy Notice.
Permissions the extension asks for
- Read pages you visit (content scripts on all sites): to check the page's language and colour its words, on your computer. Nothing is read from a page that is not in one of your languages beyond that check.
- YouTube: to show the captions panel and read the captions YouTube's player downloads.
- palimpsest.tech: to talk to your Palimpsest account.
- Storage, alarms: to keep your scores, word packs, settings and queued events, refresh them every 6 hours, and send what is queued every couple of hours.
- Context menu: adds "Look up this word in Palimpsest" to the right-click menu, and "Add to Palimpsest flashcards" when you have selected text.
- Active tab: to show, in the extension's menu, what it did on the page in front of you.
Limited use
The use of information received through the extension adheres to the Chrome Web Store User Data Policy, including the Limited Use requirements. Data is used only to provide and improve Palimpsest's learning features for you. It is not sold, not transferred to third parties except the service providers Palimpsest needs to run (hosting, database, and the AI provider that writes definitions), not used for advertising, and not used to determine creditworthiness or for lending.
Third-party material
The built-in Russian dictionary is derived from OpenCorpora
(CC BY-SA 3.0) and the Russian word list of
wordfreq (CC BY-SA 4.0). Those dictionary files are
shared under the same licences, and the extension package lists them in vendor/DATA_LICENSE.md. The analyser
that reads them is Az.js (MIT licence).
Changes and contact
If this changes what the extension sends, we will update this page and say so in the extension. Questions: see how to contact us.