Lexico Privacy Policy

Last updated: 14 September 2026

Lexico is a reading app for language learners, made by Teodor Dermendzhiev ("we"). This policy explains what the app stores, where, and why.

What Lexico stores

On your device. Your library, reading positions, flashcards and their review schedule, daily reading activity, streak, achievements and settings are stored on your device. Books you import stay on your device and are never uploaded.

In your account. When you sign in with Apple, Google or an email address, the same reading data (reading positions, flashcards, activity, streak, achievements, settings, and the titles and authors of imported books) is copied to your account so it can be restored on a new device and kept in step between your devices. Book files themselves are not uploaded.

Account details. When you sign in we receive an identifier for your account and, depending on the provider and your choices, your name and email address. Sign in with Apple lets you hide your email. We use these only to identify your account and show who is signed in.

Usage analytics. To understand how Lexico is used and improve it, the app reports what happens in it to Google Analytics for Firebase: which screens are opened, books started and finished, sentences read, words and expressions looked up (the word itself and its part of speech), conjugation tables opened, flashcards added and reviewed, purchases, settings changes, and errors. These reports are tied to your account identifier and a per-install device identifier, never to your name or email. They don't include the text of your books beyond the individual words you tap. You can switch analytics off at any time in Settings → Privacy; nothing is sent while it is off.

Translation reports. If you tell us a sentence's translation is wrong (the "Report translation" link under a sentence), we receive that sentence, its translation, where it is in the book, the reason you picked, anything you typed, the app version, and your account identifier if you are signed in. We use these only to correct the book. Reports are kept until the correction is made.

Crash reports. If the app crashes, a report (the stack trace, device model and OS version, app version, your account identifier, and a log of what the app was doing just before) is sent to Firebase Crashlytics so we can fix the problem. Some recoverable errors, such as a book that fails to open or a sync that fails, are reported the same way. Crash reports can be switched off in Settings → Privacy.

Where it's stored

Account data is stored with Google Firebase (Firebase Authentication and Cloud Firestore), usage analytics with Google Analytics for Firebase, and crash reports with Firebase Crashlytics, in data centres operated by Google. Data is transferred over encrypted connections. Only your own account can read or write your data; access rules enforce this on the server.

What we don't do

• We don't sell your data, share it with advertisers, or use it for advertising.
• We don't track you across other apps or websites, and we don't use the advertising identifier.
• We don't read your books or the words you look up for any purpose other than showing them back to you and, in aggregate, understanding which words readers look up most.

Purchases

In-app purchases are processed by Apple. We receive a transaction identifier to unlock the purchased book; we never see payment details.

Deleting your data

In the app, open Settings → Account → "Delete account…". This removes your account and all its data from our servers and from the device immediately. You can also sign out at any time, which keeps the data on the device only. Analytics data is kept by Google Analytics for at most 14 months, crash reports by Crashlytics for 90 days; both are deleted together with your account on request.

Data stored only on your device is removed when you delete the app.

Children

Lexico is not directed at children under 13 and does not knowingly collect data from them.

Changes

If this policy changes, the new version will be published at this address with an updated date.

Contact

Questions about privacy: SUPPORT_EMAIL.