Privacy Policy

Last updated: 5 November 2026

This policy explains what data the PolySubs browser extension ("PolySubs", "we") and this website handle, and why. PolySubs is built so that your learning data stays on your own device.

1. Data stored on your device

PolySubs does not run its own servers and does not require an account. The following data is stored only in your browser, using Chrome's extension storage:

• Your settings (languages, colours, positions, shortcuts). If you have Chrome Sync turned on, Chrome may sync these settings between your own devices through your Google account.
• Words you save, quiz results and learning progress.
• A cache of translations, to make the extension faster and reduce requests.
• Your Premium license key and its activation status, if you buy Premium.
• An AI provider API key, only if you choose to enter one. It is never sent anywhere except to the provider you selected.

You can delete this data at any time by removing the extension or using the "clear" buttons in its settings.

2. Data sent to third-party services

To provide its features, PolySubs sends limited data directly from your browser to these services:

• Translation: subtitle text and words you click are sent to Google Translate, or to Chrome's built-in on-device translator when available, to get translations.
• AI translation (optional): if you enter your own API key, subtitle text is sent to the provider you choose (for example Anthropic or OpenAI) under that provider's own privacy policy.
• Speaking practice (optional): when you start a speaking question, Chrome's speech recognition processes your voice. Chrome may send the audio to Google to convert it to text. PolySubs only receives the resulting text and does not record or store audio.
• Payments and licenses: payments are handled by Lemon Squeezy, our merchant of record. We never see your card details. Lemon Squeezy shares with us your email address and order details so we can provide Premium and support. Your license key is sent to Lemon Squeezy to check that it is valid.

3. What we do not do

• We do not collect your browsing history. PolySubs only runs on YouTube pages and reads the subtitles of the video you are watching, on your device.
• We do not sell, rent or share your data for advertising.
• We do not use analytics or tracking cookies in the extension or on this website.

4. Chrome Web Store limited use

The use of information received from Chrome APIs adheres to the Chrome Web Store User Data Policy, including the Limited Use requirements. Data is used only to provide the extension's features described above.

5. Children

PolySubs is not directed at children under 13, and we do not knowingly collect personal data from them.

6. Changes

If this policy changes, we will update the date at the top of this page. Significant changes will also be announced in the extension.

7. Contact

Questions about privacy: ngs.newgenservice@gmail.com