Lisen privacy policy

Last updated 2026-09-18.

Lisen is a browser extension that reads articles and PDFs aloud using a text-to-speech voice from Cartesia, with an API key you supply. It is made by one developer, runs no server of its own, and has no accounts.

What Lisen stores

• Your Cartesia API key, which you paste into the player. It is kept in Chrome's extension storage on your device and is sent only to Cartesia, as the credential for requests you start.
• Your preferences: model, voice, speed, synthesis mode, table handling, highlight colour, and where you last placed the player. Same storage.

Chrome's extension storage is not encrypted at rest. Anyone with access to your Chrome profile could read the key; treat it as you would a saved password. Removing the extension deletes everything it stored.

What Lisen sends, and to whom

When you press play, the text of the article on the page is sent to Cartesia (cartesia.ai) to be turned into speech, together with your API key and the voice and model you chose. Nothing is sent until you press play, and nothing is sent from pages where you did not open the player. Cartesia's handling of that text is governed by Cartesia's own privacy policy.

The list of voices shown in the player is fetched from Cartesia with your key when the player opens.

Opening a PDF

Clicking Lisen on a PDF opens it in Lisen's own viewer, in a new tab, so the player and read-along can work the same way they do on a web page. To render it there, Lisen fetches the PDF's own bytes: for one at a web address, from wherever it is hosted, using the access your click on it granted; for one on your computer, only if you have turned on "Allow access to file URLs" for Lisen, or if you drop the file onto the viewer yourself, in which case nothing is fetched over the network at all. That fetch goes to the PDF's own address, never to Cartesia or to the developer, and the bytes pass through the extension's own on-device storage only until the viewer has opened them. The PDF's text is then sent to Cartesia the same as an article's: only when you press play.

That is the only network traffic Lisen makes. There is no analytics, no telemetry, no crash reporting, no update check of its own, and no server run by the developer that ever sees your key, your pages, or your audio.

What Lisen does not do

• It does not sell, share, or transfer any data to anyone other than Cartesia, and to Cartesia only as described above.
• It does not use any data for advertising, profiling, or purposes unrelated to reading the page aloud.
• It does not read or send pages you have not opened the player on.

Permissions

• activeTab and scripting: to inject the player into the tab you clicked on, for that click only.
• storage: for the key and preferences above.

Lisen requests no permission to access websites in general.

Audio you download

The WAV files you save contain the synthesized speech and, in the file's metadata, the word timings for that page so read-along works when the file is opened again. They are written only where you choose to save them.

Changes

The version of this policy that applies is the one published with the extension version you have installed.

Contact

Email sudoaugustin@gmail.com, or use the support link on Lisen's Chrome Web Store listing.