Create mock APIs in seconds with Mockoon

Mockoon is a free, open-source tool that enables developers to quickly design and run mock REST APIs locally without remote deployment or accounts.

🚀 Overview

Mockoon is the easiest way to create mock APIs for local development, testing, and prototyping. It eliminates dependencies on external APIs that often have rate limits, downtime, or costs, allowing you to simulate real-world scenarios, edge cases, and errors independently.

This project solves the common pain points in software development where frontend, mobile, or fullstack teams wait for backends or struggle with unreliable third-party services. It's built for developers, testers, product managers, and teams—especially in secure or regulated environments needing offline, privacy-focused tools.

Guillaume Monnet, a self-taught full-stack developer (formerly a lawyer), created Mockoon to streamline his own workflow frustrations and share it as a lightweight, cross-platform solution. With over 8k GitHub stars and 800k+ downloads, it's trusted by thousands worldwide.

✨ Key Features

Intuitive desktop app for drag-and-drop API design, routes, responses, and headers in seconds
CLI and Docker support for self-hosting, CI/CD pipelines, and serverless deployment (AWS Lambda, etc.)
OpenAPI/Swagger import/export, proxy mode to record/replay real APIs, dynamic templating with helpers
Advanced simulation: rules engine, JSON/CSV databases, webhooks, TLS, chaos engineering for latencies/errors
Optional: Real-time collaboration via Mockoon Cloud, upcoming roadmap features like enhanced OpenAPI support

🛠 Tech Stack

Frontend: Electron, Angular, TypeScript, SCSS
Backend: Node.js (CLI & serverless packages)
Database: In-memory JSON/CSV databases
Auth: N/A (local/offline-first)
Hosting: Local, Docker, NPM packages for serverless

👥 Who Is This For?

This project is useful for:

Developers who want to prototype apps without backend dependencies
Teams looking for reliable, deterministic testing environments
Indie makers building fullstack projects needing quick API mocks

📸 Screenshots / Demo

Live demo: https://mockoon.com (download desktop app from https://mockoon.com/download/ or try CLI via NPM)
GitHub: https://github.com/mockoon/mockoon

🔥 Project Status

🟢 Actively building

Last updated: 2026-03-23

❓ FAQ

Is this project free?

Yes / Open Source (Fully free, no accounts or limits; optional paid Cloud for collaboration.)

Is the source code available?

Yes — https://github.com/mockoon/mockoon

Can I contribute?

Yes, read CONTRIBUTING.md, report issues/PRs on GitHub, join discussions, or provide feedback via the public roadmap at https://mockoon.com/public-roadmap/.