NATS

NATS is an open-source, high-performance messaging system designed for cloud-native, distributed systems, and Internet of Things (IoT) applications. Developed by Synadia, NATS stands out for its simplicity, lightweight architecture, and low latency, making it ideal for real-time messaging. It supports a variety of messaging patterns including publish-subscribe, request-reply, and queueing.

It is one of the first protocols for The Codegen Project to support, here is what is currently available through the generators (channels and client):

Languages	Core publish	Core subscribe	JetStream publish	JetStream pull subscribe	JetStream push subscription
TypeScript	X	X	X	X	X

All of this is available through AsyncAPI.