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
Send realtime application events through a Pusher-compatible WebSocket server.
Send realtime application events through a Pusher-compatible WebSocket server.
Self-host a high-performance, Pusher-compatible WebSocket server using open-source soketi instead of Fanout streaming tiers.
Requires managing your own deployment, SSL termination, and Redis message queue for horizontal clusters.
Each comparison covers the workflow described above, rather than every paid feature.