I Built a YouTube Watch-Together Extension in a...

TL;DR: My friend and I wanted to watch YouTube together from different cities. Every existing solution required a separate website or screen sharing. So I built a Chrome extension that syncs playback with a toggle. Supabase Realtime, zero backend, one afternoon, under 1,200 lines of TypeScript. You and a friend are in different cities. You want to watch the same YouTube video at the same time. Pause when they pause, seek when they seek, switch videos together. There are services for this, but th