Mockoon

Mockoon is an open-source desktop application for designing and running mock APIs locally. The desktop workflow needs neither an account nor remote deployment. It helps development and testing proceed without depending on a real service's availability, cost or rate limits.

Mock servers and responses

Create multiple local servers and routes, choose HTTP methods and status codes, set custom headers, serve files and generate JSON with templating helpers. Response rules support realistic scenarios and error cases. HTTPS, proxy forwarding and incoming/forwarded request logs help inspect integrations. OpenAPI import connects the mock design to an API specification.

Editing and testing

Mockoon 9.6 introduced OpenAPI re-import for adding routes and responses to existing mocks. Most configuration edits apply immediately; TLS settings and hostname/port changes still require a restart. Its routing migration has compatibility caveats for some older regular-expression paths. Version 9.6.1 fixes the broken macOS builds in 9.6.0.

Desktop versus deployment services

This Homebrew cask installs Mockoon.app, not the separate npm CLI. The official CLI and Docker image run mocks in headless or CI environments. Mockoon Cloud is a separate subscription service with collaboration, synchronization and deployments; cloud functionality should not be confused with the free local desktop workflow. The legacy @mockoon/serverless library is deprecated.

macOS distribution and security

The recorded 9.9.0 cask provides an Apple-silicon arm64 DMG and a separate Intel build, requiring macOS 13 or later. Install using brew install --cask mockoon. The 9.9.0 release fixes a multipart form-data prototype-pollution vulnerability (GHSA-cmwm-hp2w-h3cx); upstream recommends updating when mocks process untrusted requests or are publicly exposed.

Sources

• Official repository and README
• Official documentation
• Official 9.9.0 changelog
• Homebrew cask