Deliver realtime messages to application clients over WebSockets or server-sent events.
100% free open-source (Apache-2.0). Unlimited connections and message throughput.

Developer tools
Hold live HTTP and WebSocket connections open and push channel updates from your backend.
Hold live HTTP and WebSocket connections open and push channel updates from your backend.
Self-host the GRIP-based long-lived HTTP/WebSocket connection and channel-publishing layer used by Fanout. Does not replace Fastly global edge infrastructure, managed operations or SLA.
Requires server administration, backend integration, security, monitoring and scaling. Replaces the GRIP connection/proxy layer; no managed Fastly edge network, hosting or SLA. Free software does not include free production infrastructure. The reviewed walkthrough demonstrates local development, not production load.
Each comparison covers the workflow described above, rather than every paid feature.