Apps with 'HTTP mocking' feature

HTTP Toolkit is a beautiful, cross-platform & open-source HTTP(S) debugging proxy, analyzer & client, with built-in support for modern tools from Docker to Android to GraphQL.

Mockoon is a free and open source desktop application allowing to quickly mock servers and APIs. It packs some great features:

Mockintosh is a mock server generator that's capable to generate RESTful APIs or communicate with message queues to mimick asyncronous tasks. Such that it enables software development teams to work independently while building and maintaining a complicated microservice...

Collaboration based mock services with persistent data storage, git integration and intelligent proxying to quickly bring user flows to life.

SmartMock.io is a tool to set up, manage, and troubleshoot HTTP protocol API mocks (REST, SOAP, JSON-RPC) in the cloud. This frees you up to focus on the logic of your mocks and not have to think about boilerplate code of your own HTTP mock servers.