Zero-Dependency OpenAPI Mock Server
Paste your OpenAPI 3.x or FastAPI JSON spec to instantly generate a vanilla Node.js mock server — no Express, no npm install. Copy and run with node server.js.
// Your code will appear here...Frequently Asked Questions
Does the generated server require Express or any npm packages?
No. The output uses only Node.js's built-in http module and zero external dependencies. Run it immediately with node server.js on any machine with Node.js 16+, without running npm install.
How is this different from the OpenAPI to Express generator?
The OpenAPI to Express generator produces Express.js-specific code with router() handlers and middleware. This tool outputs pure vanilla Node.js using http.createServer() — ideal for sandboxed environments or containers where you cannot run npm install.
Can I use this with a FastAPI or Django Ninja schema?
Yes. FastAPI and Django Ninja both export standard OpenAPI 3.0 JSON at /openapi.json. Paste that JSON into the input field and the generator will produce a matching mock server for all your Python API routes.
Explore More Developer Tools
Boost your productivity with our other privacy-first utilities.
AI Mock Generator
Generate realistic mock data from natural language prompts. Runs entirely in your browser — no API keys required, no data leaves your machine.
JWT Debugger
Decode, inspect, and validate JWT token headers and payloads without sending credentials to any server. Fully offline, privacy-first debugging.
Aurora Gradient Generator
Create animated, pure CSS aurora backgrounds and mesh gradients. Generate Tailwind classes or raw CSS instantly. 100% local, privacy-first execution.