Privacy Policy
Last updated: November 15, 2026
LangTune (the Chrome extension, the Android app and this website) helps you practice English by listening to YouTube videos. This policy explains what we collect, why, who helps us process it, and how you can have it removed. Questions or requests: help@langtune.app.
What we collect
- Account. When you sign in with Google we receive your email address and your Google account identifier. We never see your Google password.
- What you save. Your flashcards (the words or phrases, their meanings and example sentences, and the video and time they came from), your checkpoints (video and start/end times) and your video history (video id, title, thumbnail, whether you favorited it, first and last time you watched it).
- Study time. To show your progress we record stretches of study: whether they happened in the extension or the app, the video, when they started, how long they lasted and your local date and time zone offset. Time is counted only while a video is really playing (or while you review flashcards). Your daily goal and reminder times are stored too.
- AI practice chat (Android app). When you talk with the AI assistant, we keep the messages you write and its replies, the more natural version of your sentences it suggests, which of your saved words you used, whether a message was spoken or typed, and a record of each AI request (which feature, which model, how much was used and when), which we use to apply the monthly allowance.
- Technical data. Our server keeps standard request logs (such as IP address, time and the page requested) for security and troubleshooting, and aggregated, non-personal performance metrics. With your consent, Google Analytics also collects website usage data (see "Cookies and analytics" below).
We do not collect your browsing history. The extension only runs on YouTube video pages, and it does not read other sites.
Cookies and analytics on this website
This website uses Google Analytics to count visits and see which pages are useful. It sets cookies (_ga, _ga_*) and sends Google your IP address (anonymized), browser and pages viewed. It only loads after you click "Accept" on the cookie notice; if you decline, nothing is loaded or stored. You can change your mind any time with "Cookie settings" in the footer. The Chrome extension and the Android app do not use Google Analytics or any advertising or tracking cookies.
What the extension does on YouTube
On a YouTube watch page the extension adds a panel to control looping and, when you turn captions on, reads the video's captions from YouTube to show them in a more readable way. That happens in your browser. Only the data listed above, the things you choose to save and your study time, is sent to our servers.
How we use it
- To provide the service: keep your words, checkpoints and history, and sync them between your browser and your phone.
- To show your study time, streaks and reminders.
- To generate example sentences for your flashcards and to power the AI practice chat and video summaries (see "Who processes your data").
- To keep the service secure and working, and to answer you when you write to us.
We do not sell your data, we do not show ads and we do not use your data for advertising or to build profiles.
Who processes your data
- Google signs you in. Their handling of that data is governed by Google's own privacy policy.
- Google Analytics measures website visits, only if you accept cookies on this site.
- OpenAI writes example sentences and powers the AI practice chat. For an example sentence we send the word or phrase, its meaning (if you saved one) and your other saved examples for that word. For the chat we send the recent messages of the conversation (and a short summary of the earlier ones) and the saved words you are practising with their meanings and one example each. We do not send your email or account details.
- Google (Gemini API) summarises videos for the chat. When you start a conversation about a YouTube video, we send Google the public link of that video, and Google processes the video's audio to write a summary. The summary is stored once per video and shared between users; it is not linked to your account.
- Your phone's speech services (on Android, provided by Google) recognise your voice and read replies aloud when you use voice in the chat, as described above.
- Google (Gemini text-to-speech) generates the AI voice for Premium accounts, from the text of the assistant's reply.
- Amazon Web Services hosts our server and database (United States, N. Virginia region) and may store encrypted backups.
- YouTube is where the videos and captions come from. Playing a video or fetching its title talks to YouTube directly, under YouTube's terms and privacy policy.
OpenAI and Google handle this data under the terms and privacy policies of their own APIs, which we do not control. AI replies can be wrong, so please do not share sensitive personal information in a conversation.
Voice (Android app). You can speak to the assistant and have its replies read aloud, for free. Your phone's speech recognition turns what you say into text, and your phone's own text-to-speech engine reads the replies. On Android the speech recognition is provided by Google and, depending on your phone and its settings, your audio may be processed on Google's servers; we do not receive or store your audio. We only receive the text it produces, which is handled like any message you type (we also note that the message was spoken). You can always use the chat with text only.
AI voice (Premium). Premium accounts can choose a more natural, AI-generated voice for the assistant's replies. For this we send the text of the reply (not your account details) to Google's Gemini text-to-speech, and a small compression service running on our own server turns the audio into an MP3. The MP3 is kept on our server for a few minutes, only until your phone has downloaded it (or it expires), and is then deleted; your phone keeps a copy in its cache so it can play it again, and removes it when you delete the conversation or sign out. It is the assistant's voice, not yours.
Because our servers are in the United States, your data is transferred outside your country. We use these providers because they offer appropriate safeguards.
Chrome Web Store user data policy
The use of information received from Google APIs, and from the Chrome Web Store, adheres to the Chrome Web Store User Data Policy, including the Limited Use requirements. We use your Google account information only to sign you in and identify your account.
How long we keep it, and deleting it
We keep your data while your account exists. A conversation with the AI assistant is kept until you delete it (long-press it, or use its bin, in the app); deleting it removes its messages. Deleting your account removes your conversations and AI usage records too. To delete your account and everything linked to it, email help@langtune.app from the address you signed in with. We delete it within 30 days; encrypted backups are overwritten within another 30 days. You can also remove individual words, checkpoints and videos inside the app and the extension.
Security
Data travels over HTTPS and is stored on a server with restricted access. On your devices, the session token is kept in secure storage. No system is perfectly secure, so please tell us right away if you suspect a problem.
Your rights
Depending on where you live (for example under Brazil's LGPD or Europe's GDPR) you can ask us to confirm what we hold about you, give you a copy, correct it, delete it, or stop processing it, and you can complain to your data-protection authority. Write to help@langtune.app and we will answer within a reasonable time.
Children
LangTune is not directed to children under 13, and we do not knowingly collect their data. If you believe a child has given us data, contact us and we will delete it.
Changes
If we change this policy in a meaningful way we will update the date above and, when it matters, tell you in the product.