Socket.IO
MIT realtime library with fallbacks, not a hosted product
Comms / Realtime · OSS/MIT · 63.2k
What's Good
MIT. Engine.IO fallbacks (WebSocket, HTTP long-polling), rooms, acknowledgements, binary. Client and server that have been in production for a decade-plus. No product pricing page because there is no product — you run the server.
The Catch
You bring the host. Horizontal scale needs Redis (or equivalent) adapter. This is not LiveKit and not a managed pub-sub. CORS, sticky sessions, and polling surprises remain your bugs.
Verdict
The MIT socket library. Free as in you run it.
Embed
[](https://stackgems.com/gems/socket-io)