Privacy policy
Lemma · Android app
Last updated: 1 October 2026
Who is responsible
CIS Studio · Clément Imbert publishes Lemma and answers for this policy. For any question about your data, write to contact@cisstudio.eu.
What leaves the phone
Lemma calls three services, and no other — all three in the European Union. Every transmission is tied to a search, to a gesture in the app, to its opening, to its going to the background (the end of the session, thirty seconds later) or to a crash; the app sends nothing when it is not running. As with any request on the Internet, the phone's IP address reaches the service called; Sentry and PostHog, for their part, do not keep it. A word selected in another app and sent to Lemma follows the path of a typed word.
LINDAT — Charles University, Prague
The form you type is sent there to be analysed, then the dictionary entry found (the lemma) to obtain its inflection tables. A word already looked up in the last seven days, for which an entry had been found, is served from the phone's cache, with no call at all.
Sentry — Germany
Two things. Each time the app opens — at launch, or on returning to the foreground after thirty seconds — a session: a random identifier created when the app was installed, the time, the version and the build, and whether the session ended in an error. No word, no log. On a crash or an unexpected error, a report: the error's trace, the last hundred or so lines of the log (so the last words looked up, the addresses called and the taps), the device (make, model, Android version, language, time zone, screen, memory, storage, battery, connection type, orientation, rooted or not), the app (version, build, permissions granted) and the same installation identifier. A crash that happened offline is kept on the phone and sent the next time the app opens. Your IP address is not kept.
PostHog — Germany
The usage statistics described below, under an installation identifier separate from Sentry's. Your IP address is not kept.
What stays on the phone
Your last fifty searches, your settings and the search cache are written on the phone and do not leave it as such: Lemma is excluded from the phone's Google backup, which copies none of it to your account. Your searches and your settings leave only with the usage statistics described below. Uninstalling the app erases everything, the installation identifiers included.
What does not exist
No account, no password, no advertising, no advertising tracker, no recording of what happens on screen. Lemma has no server: there is no profile of you anywhere. The app asks for only three Android permissions: access to the Internet, reading the network state (the connection type a crash report mentions) and access to the AnkiDroid database.
Usage statistics
Lemma counts how it is used, so that its publisher knows what to improve, and for nothing else: these statistics are never sold, never shared and never crossed with Sentry's reports. They are on by default, with no question at launch, under the consent exemption the CNIL grants to audience measurement.
What goes to PostHog: each opening of the app, with your settings (language, text size, theme, hidden sources, conjugation mode, lists shown, AnkiDroid linked or not, card options), the screen it was last left on, how long ago and what had just been opened from it (a source, AnkiDroid, a link), noted on the phone when you leave; the same at each return to the app within half an hour of leaving it; each search, with the word as typed or selected in another app, unfiltered, the way it arrived, what it returned (the card and its lemma, the heading of each of its parts and the Wiktionaries translating it, the lemmas offered, “Unknown word”, a failure), which of the three Wiktionaries answered, whether it came from the cache and how long it took; the tabs, sources, tables and lists opened; the steps of the way to AnkiDroid, and the fact that a card was added — never its front, its back or the deck's name; each tap, with the text of the element tapped, except in the Anki tab, the card sheet, the deck list and the home screen's AnkiDroid card. What is written in a field never leaves with a tap: the searched word leaves with its search. Each transmission carries the app's language. Add what the built-in browser says about itself: system and version, device model, screen size, language, time zone.
These transmissions carry an installation identifier: a number drawn at random on the phone, which designates no person. It is not extended when you use the app: after thirteen months at most, it is replaced and the phone counts as a new installation.
You can object at any time, in the app: “About”, section “What leaves the phone”, switch “Usage statistics”. Off, nothing leaves any more, not even what was waiting to be sent; one last signal, with no identifier and no other data, counts that an installation turned the statistics off, then the identifier is erased from the phone. Turning it back on starts from a new identifier. What was sent before stays until the end of its retention: objecting stops the collection without erasing the past. Sentry's reports do not depend on this switch: they are used to fix the app.
The linked sites
Under each word, a row of links opens Seznam, dict.com, the Wiktionaries or Příručka in your browser, with the word in the address. From there on, their policy and your browser's apply, not this one.
AnkiDroid
The cards you create are written into AnkiDroid, on the phone. Lemma also reads the list of your decks and their counters there, to display them; none of this leaves the phone through Lemma. If your collection syncs with AnkiWeb, that is an AnkiDroid setting, not Lemma's.
How long
Sentry keeps a session and a crash report for thirty days, then deletes them. PostHog keeps the usage statistics for one year. The history and the cache live on your phone: fifty words for the one, seven days for the other.
Your rights
Lemma processes this data on the basis of its legitimate interest: making the app work, fixing it and knowing how it is used. Its three recipients are in the European Union — LINDAT in Prague, Sentry and PostHog in Germany — and no data is transferred outside the Union.
You can ask for access to the data concerning you, its correction or its deletion, and object to its processing: write to contact@cisstudio.eu. As no report carries your name, give the approximate date and time of the crash so that it can be found. You can also lodge a complaint with the CNIL, the French data protection authority.