Privacy Policy

Effective date: October 10, 2026

This Privacy Policy explains how Lextory processes information when you use the application.

Lextory is a vocabulary-learning application for people who read books in foreign languages. It can help you save unfamiliar words and phrases, translate them, review vocabulary and use optional AI-assisted learning features.

1. Information stored on your device

Most Lextory data is stored locally on your device. This may include:

• books and series added to your library,
• saved vocabulary and translations,
• review history and learning progress,
• application settings and preferences,
• downloaded offline translation models,
• PDF files that you explicitly select for reading.

This information normally remains on your device and is not automatically uploaded to Lextory servers.

2. Installation identifier

Lextory may generate a random installation identifier for your installation of the application.

This identifier may be used to manage AI usage limits, access levels, service availability and protection against misuse of online services. It is not intended to identify you by your real name.

3. Online translation

When you use an online translation feature, the word, phrase or text you request to translate may be transmitted through Lextory's backend infrastructure to a translation provider.

Lextory currently uses Microsoft Azure Translator for online translation functionality. Requests may pass through Cloudflare infrastructure operated for Lextory.

4. AI-assisted features

Some Lextory features can use artificial intelligence to provide contextual translations, explanations, examples or other vocabulary-learning help.

When you choose to use these features, information required to process your request may be sent to Lextory's backend and an AI service provider. This may include:

• a word or phrase,
• a sentence or selected context,
• source and target languages,
• information required to provide the requested learning feature.

Lextory currently uses OpenAI services for optional AI-assisted functionality.

Complete books or PDF documents are not automatically uploaded merely because they are opened in Lextory. Only information required for a feature you actively use may be transmitted.

5. Offline translation

Lextory may use Google ML Kit for supported offline translation features. When an offline model is used, translation processing takes place on the device. Required language models may be downloaded to the device.

6. Crash reports and diagnostics

Lextory uses Sentry to help detect crashes and technical errors.

Crash reports may contain technical information such as:

• application version,
• operating system and device information,
• error messages,
• stack traces and diagnostic information.

This information is used to diagnose problems, improve application stability and fix bugs.

7. Feedback

Lextory may allow you to create and share feedback about the application. Sending feedback is optional. Feedback may include technical information such as the application version, platform and installation identifier if you choose to include it.

8. Third-party service providers

Depending on the features you use, Lextory may rely on:

• Cloudflare – backend infrastructure and security,
• Microsoft Azure – online translation,
• OpenAI – optional AI-assisted learning features,
• Sentry – crash reporting and diagnostics,
• Google ML Kit – supported on-device translation functionality.

These providers may process information according to their own privacy policies and terms.

9. Advertising and sale of data

Lextory does not use third-party advertising networks and does not sell users' personal information.

10. Data retention and deletion

Information stored locally in Lextory remains on your device until you delete the relevant content, clear the application's data or uninstall the application.

Technical server-side information such as installation identifiers, usage counters and security or anti-abuse information may be retained for as long as reasonably necessary to operate Lextory's online services, enforce usage limits, maintain security and prevent abuse.

Diagnostic information processed through third-party services may be retained according to those services' applicable retention settings and policies.

You may request deletion of developer-controlled server-side information associated with your installation by contacting the developer at the email address listed on this page.

11. Security

Reasonable technical and organizational measures are used to protect information processed by Lextory. Online communication with Lextory services uses encrypted HTTPS connections. However, no electronic transmission or storage method can be guaranteed to be completely secure.

12. Children's privacy

Lextory is not specifically designed or directed toward children and does not knowingly collect personal information from children for advertising purposes.

13. Accounts, cloud backup and subscriptions

Lextory can be used without an account. Signing in with Google is optional and is required only for AI features, cloud backup and the Premium subscription.

• Google sign-in: we receive your Google account identifier, email address and name. They are used only to identify your account, keep your session and attach your backup and subscription to it.
• Cloud backup: if you sign in, your vocabulary, reading progress and app settings are stored on Lextory servers (Cloudflare) so you can restore them after reinstalling or on another device. PDF files and book covers are not uploaded.
• AI usage limits: daily AI usage is counted per account. Words and sentences sent for AI translation may be cached on our server so the same request can be answered faster and cheaper.
• Premium subscription: payments are processed by Google Play. We never see your payment card details. We store only the purchase token and subscription status (verified with Google Play) to unlock Premium on your account.

Deleting your account: in the app go to Settings → Account and backup → Delete account. This permanently deletes your account, your backup and your stored subscription records from our servers. You can also request deletion by emailing tomasdanielkubin@gmail.com. An active Google Play subscription must be cancelled separately in Google Play. We do not sell your data.

14. Changes to this Privacy Policy

This Privacy Policy may be updated when Lextory features, data practices or third-party services change. The effective date at the top of this page will be updated when material changes are made.

15. Contact

If you have questions about this Privacy Policy or would like to request deletion of information associated with your installation, contact:

Tomáš Daniel Kubín
tomasdanielkubin@gmail.com