Mockoon API Mocking Tool

Mockoon is an open source desktop application and CLI tool that enables developers to create mock REST APIs in seconds without remote deployment or account creation. As part of the GitHub Accelerator first cohort, the project is trusted by engineering teams at Amadeus, Audi, Tesla, NHS, RBC, OneFootball, and Impala. The desktop application provides an intuitive interface for defining mock endpoints, responses, headers, status codes, and response rules, with support for dynamic templating using Handlebars syntax to generate realistic mock data including random values, UUIDs, dates, and faker data. The rules-based response system matches requests by header values, query parameters, request body content, route parameters, and cookies, enabling simulation of complex API behaviors. Mockoon supports OpenAPI specification import for generating mock endpoints from existing API definitions, HTTP request recording and replay for capturing real API responses, and proxy mode for partial mocking where unmocked requests pass through to real backends. The CLI tool and official Docker image enable running mock APIs in headless environments, CI/CD pipelines (GitHub Actions, CircleCI, TravisCI), and integration tests. A serverless package deploys mocks to AWS Lambda, Google Cloud Functions, and Firebase Functions. Mockoon Cloud offers real-time collaboration, cloud deployment, and team sharing features. Rated 4.5 on G2 and Capterra and 5 on Product Hunt, the project is built in Europe with privacy-first principles.