# Mockoon — Desktop API Mocking Made Simple

> Mockoon is a free, open-source desktop application for creating mock REST APIs in seconds. It provides a visual interface to define endpoints, responses, and rules without writing code.

## Install

Save in your project root:

# Mockoon — Desktop API Mocking Made Simple

## Quick Use
```bash
# Install via npm (CLI version)
npm install -g @mockoon/cli

# Start a mock from an exported environment file
mockoon-cli start --data ./my-api.json --port 3001

# Or install the desktop app
# macOS: brew install --cask mockoon
# Linux: download AppImage from GitHub releases
# Windows: download installer from mockoon.com
```

## Introduction
Mockoon is a free, open-source tool for creating mock HTTP APIs without writing code. It was built to solve the problem of frontend developers waiting on backend teams by providing a fast way to simulate any API locally. It runs as a desktop app or a CLI for CI integration.

## What Mockoon Does
- Creates mock REST API endpoints with custom HTTP methods, paths, and status codes
- Returns dynamic responses using a built-in templating system with Handlebars
- Simulates latency, errors, and sequential responses for realistic testing
- Supports request logging to inspect incoming calls during development
- Exports and imports environment files for sharing mocks across a team

## Architecture Overview
Mockoon is an Electron-based desktop application with an Express.js server running under the hood. Each mock environment spawns an independent Express server on a user-defined port. The CLI version (`@mockoon/cli`) uses the same Express-based core without the Electron shell, making it suitable for Docker and CI pipelines. Configuration is stored as JSON files.

## Self-Hosting & Configuration
- Install the desktop app from the official site or via package managers
- Use the CLI (`@mockoon/cli`) for headless operation in Docker or CI
- Define environments as JSON files that can be version-controlled
- Configure proxy mode to forward unmatched requests to a real backend
- Set up HTTPS with custom certificates for testing TLS-dependent clients

## Key Features
- No-code visual editor for defining routes, headers, and response bodies
- Handlebars-powered response templating with access to request data
- Proxy mode that forwards unmatched routes to a live API server
- CORS pre-configured by default to work with browser-based frontends
- CLI and Docker support for running mocks in automated test pipelines

## Comparison with Similar Tools
- **Postman Mock Server** — cloud-based mocking tied to a Postman account and paid plans
- **WireMock** — Java-based mock server with more advanced matching but heavier setup
- **JSON Server** — quick REST API from a JSON file but limited templating and no GUI
- **MSW (Mock Service Worker)** — intercepts requests in the browser but not a standalone server
- **Prism** — generates mocks from OpenAPI specs but less flexible for custom responses

## FAQ
**Q: Is Mockoon free for commercial use?**
A: Yes. Mockoon is MIT-licensed and free for any use including commercial projects.

**Q: Can I run Mockoon in Docker?**
A: Yes. Use the CLI package (`@mockoon/cli`) with the official Docker image or build your own.

**Q: Does Mockoon support OpenAPI import?**
A: Yes. You can import OpenAPI/Swagger specifications to auto-generate mock endpoints.

**Q: Can multiple developers share the same mock configuration?**
A: Yes. Export the environment as a JSON file and commit it to version control for the team to share.

## Sources
- https://github.com/mockoon/mockoon
- https://mockoon.com/docs/latest/about/

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Author: AI Open Source