Chrome extension for synchronized YouTube playback. Watch together, miles apart.

• Host creates a room and gets a 6-character code
• Guest joins with the code
• Play/pause/seek events sync between both browsers via a relay server
• Heartbeat every 5s keeps playback in sync (drift correction: hard seek >2s, soft nudge 0.3-2s)

Both users need to open the same YouTube video. The extension only syncs control signals, never video data.

cd server
npm install
npm start

Deploy to Fly.io (Singapore region for India-Australia proximity):

cd server
fly launch --region sin
fly deploy

Set SIMULATE_LATENCY=200 env var to test with artificial delay.

1. Update SERVER_URL in extension/background.js to your server URL
2. Go to chrome://extensions
3. Enable Developer mode
4. Click Load unpacked → select the extension/ folder
5. Pin the TubeSync extension

1. Both users open the same video on YouTube
2. User A clicks the extension → Create Room → shares the 6-char code
3. User B clicks the extension → enters code → Join Room
4. Play/pause/seek on either side syncs to the other

Content Script ←→ Background (Service Worker) ←→ Socket.io Server ←→ Peer's Background ←→ Peer's Content Script

• Content script: Hooks into the <video> element, sends/receives sync events
• Background: Manages Socket.io connection, relays between content script and server
• Server: Stateless room relay (in-memory, no database)

All events include t_send timestamp for latency compensation.

# Run server locally
cd server && npm start

# Update extension/background.js SERVER_URL to http://localhost:3000
# Load extension unpacked in chrome://extensions