KoalaSync

KoalaSync is a lightweight browser extension that keeps you and your friends perfectly in sync on YouTube, Netflix, Twitch, Prime Video, Jellyfin, Emby, and almost any other site with an HTML5 video player. Press play once and everyone stays together. It’s built privacy-first: no accounts, no telemetry, and the official relay server runs entirely in volatile RAM with zero persistence, so nothing about your sessions is ever stored. Open source under the MIT license and fully self-hostable with a single Docker command, KoalaSync is a transparent watchparty tool that works everywhere and respects your data sovereignty.