HttpMaster - HttpMaster is a professional software tool for testing and debugging HTTP applications, primarily aimed at REST API applications and web services.
Loader.io - Loader.io is a simple cloud-based load testing service
Hoppscotch - Open source API development ecosystem
LoadFocus - Cloud Testing Infrastructure | Cloud Testing Services and Tools for Websites & APIs.
Request inspector - Debug web hooks, http clients
Loadium - Performance Testing & Load Testing Tool