Open-source project by Vladimir Dementyev that enhances (rather than replaces) Action Cable by extracting the WebSocket server out of MRI. Clients connect to an external WebSocket server written in Go (or Erlang), which proxies Action Cable protocol messages to the Rails application over gRPC (HTTP/2 + protobuf). Redis (or similar) is used to broadcast messages from the app back to the WebSocket server, which fans them out to clients. Supports nearly all Action Cable features with almost no channel rewrites. Offers additional capabilities: zero-disconnect deployment (the stateless proxy stays up while the Rails app is reloaded, avoiding thundering-herd reconnects), and a Prometheus-compatible metrics endpoint for Grafana dashboards and alerting. In a production case study (equestrian-shows platform), migrating from Action Cable to AnyCable took a couple of weeks and reduced Heroku usage from 21 2×-dynos (1 GB each) to 4 smaller dynos, ~10× cost reduction.