Privacy Policy — Lingtune

1. Data stored on your device

By default all learning data stays in the extension's storage in your browser (IndexedDB / chrome.storage) and never leaves your device:

• Settings (learning language, translation language, appearance, subtitles…).
• Words and sentences you save, with the video ID and timestamp for replay.
• Pronunciation practice recordings and review progress.
• Downloaded IPA pronunciation dictionaries (cache).

2. How long data stays on your device

So the extension doesn't take up too much browser storage, some data is deleted from your device automatically:

• Recordings that were never synced to a cloud account (not signed in, “Sync voice recordings” off, or the upload failed) are permanently deleted if not played for 7 days. The saved sentence itself is kept.
• Practice recordings of sentences you haven't saved are kept for 7 days.
• Recordings synced to your account: if not played for 15 days, only the audio copy on your device is removed; the one in your account stays and is downloaded again automatically when you play it.
• IPA dictionaries of a language not used for 60 days are deleted and downloaded again when needed. Cached translations stop being used after 15 days unused and are removed from your device at the next periodic cleanup (at most 2 weeks later, while the extension is running).
• The dashboard also caches translations in your browser (IndexedDB) so they don't have to be fetched again when you reopen a page. This cache holds only the original sentence/word and its translation, up to 30 MB; it isn't tied to your account and stays after you sign out. Cached translations stop being used after 15 days unused and are removed at the next periodic cleanup (at most 2 weeks later, while you have the dashboard open). You can remove it right away by clearing the dashboard's site data in your browser settings.
• When you're signed in, words/sentences you delete or unsave in the dashboard are removed from the extension too, along with their recordings.

3. Data sent so the extension can work

• Translation: the subtitle text you ask to translate is sent to MyMemory (api.mymemory.translated.net, operated by Translated srl) without any account information. If MyMemory does not respond, the text is sent to our translation server (api.lingtune.com, running self-hosted LibreTranslate); the server does not store translated content.
• Subtitle fallback: only when subtitles can't be read directly from YouTube, the extension sends the video ID and language code to api.lingtune.com to fetch subtitles. Subtitles of public videos may be cached on the server.
• IPA dictionaries: the extension downloads pronunciation dictionary files (data, not executable code) from api.lingtune.com. These requests contain no personal data.
• Speech recognition: when you press the pronunciation practice button, the extension uses your microphone and the browser's built-in Web Speech API to score your pronunciation. The first time, Chrome asks whether to allow Lingtune to use your microphone; the permission goes to the extension only, never to the YouTube page. In Chrome, audio for speech recognition may be processed by Google under Google's policies. The microphone is only on from the moment you start a practice take until you press score.

4. Anonymous error reports

This is off by default. If you turn on “Send anonymous error reports” in settings, the extension sends technical error reports (error message, stack trace, extension/browser version, YouTube interface language and region) to api.lingtune.com. Reports carry no account or cookies; emails, tokens and URL paths are stripped before sending. Like any network request, the server sees the request's IP address. Reports are deleted automatically after 30 days. You can turn it off again at any time.

5. Cloud account (optional)

You don't need an account to use the extension. If you choose to create one and sign in to review in the dashboard, we store on our server:

• Your email and password (stored only as a hash, never in plain text).
• Saved words and sentences (with the video ID, title and timestamp), review history and learning settings.
• Subtitles of the videos you choose to practice with on the web.
• Pronunciation recordings — only if you turn on “Sync voice recordings to the cloud account” in settings (off by default). When off, new recordings stay on your device; ones uploaded earlier remain on the server until you delete them or your account. The extension removing its local copy (section 2) never deletes the one on the server.
• The IDs of words/sentences you deleted (no content), kept for up to 1 year so the extension on each of your devices can delete them too. For this, and to download recordings back, the extension periodically sends the IDs of its synced items to api.lingtune.com.
• Your plan and upgrade requests. Payment is by bank transfer via QR code; we never receive or store card details.

6. What we don't do

• We don't track your browsing history. The extension only runs on www.youtube.com and only sends video IDs in the cases listed in sections 3 and 5.
• We don't download YouTube videos or audio.
• We don't sell, rent or share user data with third parties, except the services in section 3 that the features require.
• We don't use data for advertising, credit scoring, or anything unrelated to language learning.
• We don't run remotely hosted code.

7. Chrome Web Store compliance

Lingtune's use and transfer of information received complies with the Chrome Web Store User Data Policy, including the Limited Use requirements.

8. Security

All connections to our servers use HTTPS. Access to data on our servers is limited to operating the service.

9. Your rights

• Export your data from the extension's popup and delete any saved item from the sidebar or the dashboard (deleting in the dashboard removes it from the extension too when you're signed in); uninstalling the extension removes all local data.
• Turn on “Sync voice recordings” to keep recordings you haven't played for more than 7 days (section 2).
• Turn anonymous error reports and recording sync on or off in settings.
• Ask to access, correct or delete your cloud account and all its data by emailing [email protected]. We respond within 30 days.

10. Children

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

11. Changes and contact

When this policy changes, the date at the top of the page is updated. Questions: [email protected].