What it does
Mockoon lets developers design and run mock HTTP APIs without waiting for a real backend or sending every test request to a third-party service. Its desktop application edits environments and routes locally, while the CLI can run the saved mock data in headless environments and CI. Routes can return configured bodies, headers, and multiple responses; request rules and templating help model cases that are awkward to produce from a live dependency.
Build a response before the backend exists
Create a mock environment and add an HTTP route for the path your client expects. The route documentation says a new route starts with a 200 response and an empty body, which you can replace with the status, headers, and payload needed by the test. A frontend can then point its API client at the local mock while the real backend is still in progress, or a test can use a fixture that reliably returns an error or edge case. Mockoon stores each desktop environment in a JSON data file that can be kept in Git and shared with another user. For automation, the official CLI quick start runs that file with mockoon-cli start --data ./data-file.json; the same tool is available for Docker and CI workflows. The local desktop app and CLI are free and published under the MIT license. Mockoon Pro is a separate paid offering for synchronized collaboration, web access, and mock deployments. One practical modeling limit is that HTTP routes are stateless and independent by default. Use the documented data-bucket or CRUD-route features when an API test needs shared or mutable state rather than expecting every endpoint to remember earlier calls.
Strengths
- Local mock servers can provide controlled status codes, response bodies, headers, delays, and dynamic data.
- Environment files are JSON and can be versioned or shared through Git.
- The CLI can run those mocks in Docker, CI jobs, or other headless environments.
- The desktop application and CLI are free and the official repository uses the MIT license.
Watch out for
- HTTP routes are independent and stateless by default; shared or mutable state needs additional data-bucket or CRUD-route configuration.
- Real-time collaboration, synchronized environments, and remote mock deployments are part of the separate Mockoon Pro offering.
Best for
- Frontend developers working before backend endpoints are ready
- Integration tests that need repeatable API responses and edge cases
- Teams running local API fixtures in a CI pipeline
Sources
- Create mock APIs in seconds with Mockoon (Oct 25, 2026)
- Mockoon HTTP routes documentation (Oct 25, 2026)
- Sharing your mock API files (Oct 25, 2026)
- Self-host your mocks with Mockoon CLI (Oct 25, 2026)
- Mockoon Pro pricing (Oct 25, 2026)
- mockoon/mockoon: Mockoon: awesome API mocking (Oct 25, 2026)
- mockoon/LICENSE.md at main · mockoon/mockoon · GitHub (Oct 25, 2026)