LenguaZen: Spanish, French & Italian writing practice with AI

Last updated: August 28, 2026

What we collect

LenguaZen collects your email address for authentication and stores your learning data (journal entries, word bank, video library, practice progress) to provide the service.

Chrome Extension

The LenguaZen Chrome extension connects to your account through a revocable access token (not your browser session), created when you approve the connection at lenguazen.com. You can disconnect it at any time from the extension popup, which immediately invalidates the token server-side.

Once connected, the extension has these features:

Add video (always on): when you click the LenguaZen button on a YouTube video page, the extension sends that video's URL to lenguazen.com so it can be added to your library. Nothing is added to your library until you click the button.
Track watch time (off by default): if you turn this on in the extension popup, the extension will record time you spend actively watching YouTube or Netflix (beta) videos whose audio language matches one of your selected learning languages. For each qualifying video it sends the following to lenguazen.com: the video's platform ID and URL or title, channel name, thumbnail URL, duration, detected language, and seconds watched. These videos appear in your library with no transcript until you choose to import one (YouTube) or until the Subtitle Overlay loads for that title (Netflix). The extension does not record videos outside your target languages, does not track browsing outside youtube.com/watch and netflix.com/watch pages, and stops recording immediately when you turn the toggle off.
Subtitle Overlay and word lookups: the overlay shows the video's subtitles over the player with translations and vocabulary highlighting. On YouTube it turns on only when you tap the LenguaZen pill on a video page. On Netflix (beta) it loads automatically when you open a title that has subtitles in the language you are learning: the extension downloads that subtitle file from Netflix directly (our servers never request anything from Netflix) and sends the subtitle text to lenguazen.com so the overlay can be built. On any page in a language you are not learning, the overlay does nothing and sends nothing. Tapping a word to look up its meaning, or saving a word to your Word Bank, sends that word and its sentence context to lenguazen.com the same way the LenguaZen reader does. While the overlay is on, the subtitle lines you play through are recorded as vocabulary exposure, exactly as they are when you watch inside LenguaZen.

The extension never sells or shares data with third parties, does not run analytics, and only communicates with lenguazen.com.

Analytics

With your consent, we use PostHog to understand how the app is used (page views, clicks, feature usage, session recordings). PostHog is hosted in the EU and acts as a data processor under our agreement with them. Data collected includes your user ID, email, IP address, device and browser info, and in-app interactions.

Before you decide, an anonymous id is kept in your browser's session storage for the visit; no cookies are set. If you accept, we set cookies and link your activity to your account. If you decline, all analytics collection stops and that stored id is cleared. Your choice itself is remembered in a cookie and in site storage. To change it later, clear cookies and site data for this site and reload.

Data sharing

We do not sell or rent your personal data. We use the following third-party processors: OpenAI (AI corrections and suggestions on your learning content), PostHog (product analytics, with your consent), Resend (transactional email), and Railway (hosting and database). Each processes data only as needed to provide the service. We use OpenAI's API, whose terms exclude API content from being used to train their models.

Data storage & retention

Your data is stored in a PostgreSQL database hosted on Railway. Watch-time data collected by the extension is retained for as long as the associated video remains in your library; removing a video also removes its watch-time counter. You can request deletion of your account and all associated data by contacting us.

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