WireMock : Free and Open Source tool for building mock APIs. Create stable development environments, isolate yourself from flakey 3rd parties and simulate APIs t...
gRPC : gRPC is a modern, open source remote procedure call (RPC) framework that can run anywhere. It enables client and server applications to communicate tr...
Novu : Novu provides a unified API that makes it simple to send notifications through multiple channels, including In-App, Push, Email, SMS, and Chat. With N...
Cool QL Cool : CoolQLCool (CQC) is an open source GraphQL server that allows you to turn websites into GraphQL APIs.
httpbin.org : A simple HTTP Request & Response Service.
Mockoon is the easiest and quickest way to design and run mock APIs. No remote deployment, no account required, free and open-source.