WatchSync Privacy Policy
Last updated: October 26, 2026
WatchSync is a browser extension that keeps a video playing in sync between you and your friends. Each person plays the video on their own computer and their own account. WatchSync only sends small "play / pause / seek" messages between you. It never sees, records or transmits the video itself.
In short
- No accounts, no passwords, no email address.
- Your username and friends list are stored only in your browser.
- The relay server keeps information in memory only while you are connected, writes nothing to disk, and keeps no logs.
- No analytics, no ads, no tracking, and nothing is ever sold or shared with anyone else.
What is stored in your browser
Using Chrome's extension storage on your own computer:
- the username you choose;
- a random device ID, generated by the extension, so that the server can tell your own reconnects apart from someone else using your username;
- your friends list (the usernames you add);
- the server address, if you change it in Settings;
- while your browser is open: the room you're in and pending invites.
Uninstalling the extension deletes all of this.
What is sent to the relay server, and why
| Information | Why |
|---|---|
| Your username and device ID | To show you as online to friends who added you, and to keep two people from using the same name at the same time. |
| The usernames on your friends list | So the server can tell you which of them are online. Only whether each is online comes back. |
| The room code, and the address and title of the video page you start a room on | So the people in your room, and friends you invite, can open the same video. |
| Playback state: playing or paused, position, speed, and whether your player is buffering | To keep everyone in the room in sync. Only for the tab you're using in a room. |
| Invites you send | To deliver them to the friend you invited. They're only delivered if that friend has added you as a friend too. |
| Clock-sync timestamps | To measure the difference between your clock and the server's, so everyone can start at the same moment. |
This information is held in the server's memory only while you are connected, and is forwarded only to the people in your room or the friend you invite. When you disconnect it is discarded. The server has no database and keeps no logs of these messages.
WatchSync doesn't read anything else from the pages you visit. It only looks at the video player on supported video sites (YouTube, Twitch, Vimeo and Netflix), and only acts in a tab you have started or joined a room in. It never reads your account details, watch history, cookies, or anything typed on a page.
Hosting
The relay server runs on Cloudflare Workers. Like any internet service, Cloudflare's network handles technical connection data, such as your IP address, to deliver traffic. That's covered by Cloudflare's privacy policy. WatchSync doesn't receive or keep this data.
Children
WatchSync is not directed at children under 13 and doesn't knowingly collect information from them.
Changes
If this policy changes, the new version will be posted at this address with a new date.
Contact
Questions? Use the contact details on WatchSync's Chrome Web Store page.