Repolode
Submit
ThreeDotsLabs

ThreeDotsLabs/watermill

A Go library for building event-driven applications, with a unified Publisher/Subscriber interface over Kafka, RabbitMQ, NATS, SQL and more.

View on GitHubWebsite
Stars
9,927
Forks
515
Open issues
86
Last commit
2 months ago

What is it?

Watermill is a Go library for working with message streams. It targets event-driven applications and patterns such as event sourcing, CQRS, sagas, and RPC over messages. Its core abstraction is a handler that receives a message and returns new messages or an error, with middleware deciding what happens next.

The library defines a common Publisher and Subscriber interface, so the same application code can run on several backends. Supported Pub/Subs include Kafka, RabbitMQ (AMQP), NATS JetStream, Redis Streams, Google Cloud Pub/Sub, AWS SNS/SQS, and SQL databases (MySQL and PostgreSQL), plus an in-memory GoChannel for local use. Pub/Sub implementations live in separate repositories under the ThreeDotsLabs organization.

The project is at v1.0.0 and describes its Pub/Sub implementations as tested with shared test suites run under the race detector and in parallel stress mode. It also publishes a benchmark table comparing throughput across backends on a single test setup.

Key features

  • 01Common Publisher and Subscriber interfaces across many message brokers
  • 02Handler-based model where handlers return new messages or errors
  • 03Middleware for composing behavior such as retries and processing flow
  • 04Supports Kafka, RabbitMQ, NATS JetStream, Redis Streams, Google Cloud Pub/Sub, AWS SNS/SQS and SQL databases
  • 05In-memory GoChannel for local development and testing

Use cases

  • Building event-driven services that exchange messages between components
  • Implementing event sourcing or CQRS read models in Go
  • Coordinating long-running workflows with sagas
  • Switching message brokers without rewriting application logic

Quick start

  1. 1

    Install the Watermill library module

    go get github.com/ThreeDotsLabs/watermill
  2. 2

    Follow the Quickstart guide on the official site to write your first app

Things to know

  • It is a Go library, so it only helps if you build applications in Go.
  • Each Pub/Sub backend such as Kafka or RabbitMQ lives in a separate module that you must add yourself.
  • Benchmark numbers are rough estimates and depend heavily on setup.

Topics

#event-driven#messaging#pub-sub#cqrs#event-sourcing#kafka#rabbitmq#nats#events#go

FAQ

What is watermill?
A Go library for building event-driven applications, with a unified Publisher/Subscriber interface over Kafka, RabbitMQ, NATS, SQL and more. Watermill is a Go library for working with message streams. It targets event-driven applications and patterns such as event sourcing, CQRS, sagas, and RPC over messages. Its core abstraction is a handler that receives a message and returns new messages or an error, with middleware deciding what happens next.
Is watermill free to use? What license does it have?
watermill is open source under the MIT license. Check the license terms before using it in commercial products.
Is watermill still maintained?
Updated within 6 months. The last commit to watermill was on Aug 25, 2026.
What can I use watermill for?
Building event-driven services that exchange messages between components Implementing event sourcing or CQRS read models in Go Coordinating long-running workflows with sagas Switching message brokers without rewriting application logic
How do I install watermill?
Install the Watermill library module: go get github.com/ThreeDotsLabs/watermill Follow the Quickstart guide on the official site to write your first app
Where can I get watermill?
The source code and installation instructions are on GitHub: https://github.com/ThreeDotsLabs/watermill

Summary generated by AI from the project's README. GitHub stats refresh daily.

Related projects