Centrifugo

Scalable real-time messaging server in a language-agnostic way.

Centrifugo is an open-source scalable real-time messaging server. It instantly delivers messages to application online users connected over supported transports (WebSocket, HTTP-streaming, Server-Sent Events (aka EventSource), GRPC, WebTransport). Centrifugo has the concept of channel subscriptions – so it's a user-facing PUB/SUB server.

Centrifugo is language-agnostic and can be used to build chat apps, live comments, multiplayer games, real-time data visualizations, collaborative tools, AI streaming responses, etc. in combination with any backend. It is well suited for modern architectures and allows decoupling the business logic from the real-time transport layer.

The core idea of Centrifugo is simple – it's a PUB/SUB server on top of modern real-time transports:

Your backend communicates with Centrifugo over a simple HTTP or GRPC API to publish messages into channels, while clients subscribe to those channels using one of the official SDKs (or the unidirectional approach with no SDK dependency).

Quick start

Spin up Centrifugo with its embedded admin UI using Docker:

docker run -it --rm -p 8000:8000 centrifugo/centrifugo:latest centrifugo \
  --client.insecure --admin.enabled --admin.insecure
# ^ insecure flags: for local trial only, never use in production

Then open http://localhost:8000 to reach the admin UI, where you can watch live connections and publish messages into channels. The insecure flags above remove authentication for a frictionless local trial only – never use them in production.

For native binaries, Homebrew, packages, and production configuration see the installation instructions, and follow the quickstart tutorial to connect your first client.

Why Centrifugo

The hard part is to make the PUB/SUB concept production-ready, efficient, flexible and available from different application environments. Centrifugo is a mature solution that already helped many projects with adding real-time features and scaling towards many concurrent connections. It provides a set of features not available in other open-source solutions in the area:

• Efficient real-time transports: WebSocket, HTTP-streaming, Server-Sent Events, GRPC, WebTransport (experimental)
• Built-in scalability with Redis (or Redis Cluster, or Redis-compatible storage – ex. AWS Elasticache, Valkey, KeyDB, DragonflyDB, etc), PostgreSQL or Nats.
• Simple HTTP and GRPC server API to communicate with Centrifugo from the app backend
• Asynchronous PostgreSQL and Kafka consumers to support transactional outbox and CDC patterns
• Flexible connection authentication mechanisms: JWT and proxy-like (via request from Centrifugo to the backend)
• Channel subscription multiplexing over a single connection
• Rich subscription model: stream (client-side and server-side), map, shared poll, and proxy subscription streams
• Various channel permission strategies, channel namespace concept
• Hot message history in channels, with automatic message recovery upon reconnect, cache recovery mode (deliver latest publication immediately upon subscription)
• Delta compression in channels based on Fossil algorithm
• Online channel presence information, with join/leave notifications
• A way to send RPC calls to the backend over the real-time connection
• Strict and effective client protocol wrapped by several official SDKs
• JSON and binary Protobuf message transfer, with optimized serialization and built-in batching
• Beautiful embedded admin web UI
• Great observability with lots of Prometheus metrics exposed and official Grafana dashboard
• And much more, visit Centrifugo documentation site

Client SDKs

Official SDKs wrap Centrifugo's bidirectional protocol and handle reconnects, subscription state, message recovery, and more across platforms:

For simple use cases Centrifugo also supports a unidirectional approach (WebSocket, SSE, HTTP-streaming, GRPC) that needs no SDK – any standard client for the transport works. See the transports overview and the client protocol spec for details.

Documentation

• Centrifugo official documentation site
• Installation instructions
• Getting started tutorial
• Design overview and idiomatic usage
• Build a WebSocket chat/messenger app with Centrifugo tutorial
• Centrifugal blog
• FAQ
• Examples repository

Community

• Telegram
• Discord
• X (Twitter)

Found a bug or have an idea? Open an issue. Want to contribute? See CONTRIBUTING.md.

Backing

This repository is hosted by packagecloud.io.

Also thanks to JetBrains for supporting OSS (most of the code here written in Goland):