WireMock

WireMock is an API simulation tool that mocks the HTTP APIs an application depends on, so that it can be developed and tested when the real services are unavailable, unstable or costly to call.

The open source core is available for Java and .NET and can run embedded in tests or as a standalone server. WireMock Cloud is a commercial hosted offering that adds AI-assisted features, and WireMock Runner is also offered to run simulations.

The open source WireMock is distributed under the Apache License 2.0 and is actively developed on GitHub.