Top 3 Go Eventsource Projects

Centrifugo

31 7,914 9.0 Go

Scalable real-time messaging server in a language-agnostic way. Self-hosted alternative to Pubnub, Pusher, Ably. Set up once and forever.

Project mention: WebSockets vs. Server-Sent-Events vs. Long-Polling vs. WebRTC vs. WebTransport | news.ycombinator.com | 2024-03-20

Hello, I am author of https://github.com/centrifugal/centrifugo. Our users can choose from WebSocket, EventSource, WebTransport (experimental stabilize in the future). WebRTC is out of scope as the main purpose is central server based real-time json/binary messaging, and WebRTC makes things much more complex since it shines for peer-to-peer and rich media communications.
What I'd like to add is that Centrifugo also supports HTTP-streaming – not mentioned by the OP – but this is a transport which has advantages over Eventsource - like possibility to send POST body on initial request from web browser (with SSE you can not), it supports binary, and with Readable Streams browser API it's widely supported by modern browsers.
Another thing I'd like to mention about Centrifugo - it supports bidirectional WebSocket fallbacks with EventSource and HTTP-streaming, and does this without sticky sessions requirement. I guess nobody else have this at this point. See https://centrifugal.dev/blog/2022/07/19/centrifugo-v4-releas.... Which solves one more practical concern. Sticky sessions is an optimization in Centrifugo case, not a requirement.
If you are interested in topic, we also have a post about WebSocket scalability - https://centrifugal.dev/blog/2020/11/12/scaling-websocket - it covers some design decisions made in Centrifugo.

centrifuge

13 979 8.5 Go

Real-time messaging library for Go. The simplest way to add feature-rich and scalable WebSocket support to your application. The core of Centrifugo server.

Project mention: Centrifugo v5 - new major release of real-time messaging server written in Go | /r/golang | 2023-06-29

BTW, Centrifugo is based on https://github.com/centrifugal/centrifuge Go library which may provide much more control and flexibility for Gophers than a standalone server and can be embedded to any Go app leveraging all Centrifugo client SDKs.

InfluxDB

www.influxdata.com sponsored

Power Real-Time Data Analytics at Scale. Get real-time insights from all types of time series data with InfluxDB. Ingest, query, and analyze billions of data points in real-time with unbounded cardinality.
sseserver

1 107 3.4 Go

:surfer: High-performance Server-Sent Events endpoint for Go

NOTE: The open source projects on this list are ordered by number of github stars. The number of mentions indicates repo mentiontions in the last 12 Months or since we started tracking (Dec 2020).