Privacy Policy

Effective 2026-10-28. Linesub is made by PRODUCTIVITY TOOLS LIMITED, Hong Kong. Questions: support@productivitytools.app.

Your video stays on your phone

When you add subtitles to a video, the app takes the video's sound out on your phone and sends only the sound to our server. The picture never leaves your phone; the app writes the subtitles into a copy of the video on the phone.

Our server sends the sound to Groq, which writes down what is said, and the written text to OpenAI, which translates it into the language you chose. The sound exists on our server only while your video is being processed and is deleted when the job ends; we do not save it, back it up or listen to it. The subtitle text is kept with the job for 24 hours after it is ready, so the app can fetch it again after a lost connection, and is then deleted. We keep a fingerprint of the sound (a SHA-256 hash, which cannot be turned back into the sound) to refuse a sound that keeps failing.

Groq does not keep the sound by default; it may log a request for up to 30 days to fix errors or investigate abuse. OpenAI does not use the text to train its models; it keeps abuse-monitoring logs for up to 30 days. We ask OpenAI not to store the translation.

What we do keep

• App identifier. An id that stands for your phone; there is no account, name or email. On Android it is the Android ID your phone gives this app (every app gets its own), so it stays the same if you reinstall. On iOS it is a random id kept in your phone's keychain. The id counts your minutes and links your purchases.
• Job log. For every video: the app identifier, your IP address, the length of the sound, the video's size in pixels, the spoken and the chosen language, how long it took and what it cost, the app version, and your phone's language and region. Used to count minutes, to enforce the limits, to spot abuse and to understand how the app is used. Deleted or anonymised within 12 months.
• Reports. If you report subtitles, we keep the reason you gave and the log entry of that video.
• Purchases. Payment goes through Google Play or the App Store; we never see your card. RevenueCat, our purchase service, receives the app identifier and the store receipt to tell us which minute packs you bought.

The app contains no analytics or advertising SDKs. We do not sell or share data for advertising.

Where it is processed

Our server and database run on Railway; speech is written down by Groq and translated by OpenAI; purchases are handled by RevenueCat. Each processes data only to provide the service described here.

Children

The app is for adults. We do not knowingly collect data from anyone under 18. Videos you choose remain your responsibility; choose videos you have the right to use.

Your rights

Email us to delete the log entries tied to your app identifier (send the support code from the Minutes screen in the app) or to ask what we hold. Videos with subtitles are kept only on your phone; delete them there.

Changes

Updates are posted on this page with a new effective date.