Mockoon

Mockoon is a free, open-source desktop application that allows for quick server and API mocking. It includes some great features: Unlimited mocking: Create an unlimited number of mock APIs and routes and run them in parallel. Import/Export: Mock API import/export, supporting Swagger/OpenAPI formats. Route regex: Supports route regular expressions (e.g., /.*, /[a-z]{3}, ...), based on ExpressJS syntax. Multiple responses per route: Provide multiple rule-triggered responses for each route with any header, body, or HTTP status code. CORS: Automatically sends CORS headers (e.g., Access-Control-Allow-Origin) for OPTIONS requests. HTTPS: Serve your mock APIs over TLS with self-signed certificates. Response headers: Add any response headers to your routes and mock APIs. Features autocomplete. Latency: Add latency at the environment or route level, or even both. Request and response logging: Log all incoming requests and outgoing responses for easy debugging. Proxy mode: Use Mockoon's proxy mode to redirect all undefined routes to a specified host. File serving: File serving with automatic MIME type detection and template support. Rich text editor: A rich text editor for body content, supporting multiple languages (JSON, HTML, etc.). Templating: Body, file content, and headers support templating, with many helpers: URL params, query params, JSON body lookups, etc. Auto-save: Real-time auto-save as you type. Never worry about saving again! Offline: No accounts, no sign-ups, no cloud deployments.

Mockoon is a free, open-source desktop app that helps developers quickly create and run mock API servers, saving development time and simplifying API integration testing.