Gotify：简单的发送和接收消息的服务器
We wanted a simple server for sending and receiving messages (in real time per WebSocket). For this, not many open source projects existed and most of the existing ones were abandoned. Also, a requirement was that it can be self-hosted. We know there are many free and commercial push services out there.
https://github.com/gotify/server
https://gotify.net