Mockoon
A free, open-source tool for designing and running mock APIs locally, combining a desktop app with a CLI for headless and CI environments and optional cloud collaboration.
Mockoon is a tool for designing and running mock APIs without a remote deployment or an account. A desktop application designs and runs mock servers locally, and a companion CLI self-hosts the same fake APIs headlessly, including in CI; a paid cloud offering adds team collaboration and hosted deployment of mock APIs.
Mocking an API speeds up development and third-party integration by removing dependence on external services' rate limits, cost and availability, and lets an application be tested against predictable responses, status codes and latencies, including simulated edge cases and errors, while onboarding new team members with a consistent test environment.
Features include unlimited local mock servers and routes, OpenAPI compatibility, request/response logging, JSON templating, proxy forwarding and HTTPS support, and the CLI is also distributed as an npm package and an official Docker image for use in serverless environments.