Mock API Generator

Define mock API endpoints and export as Express, Flask, or JSON Server config.

Free & unlimited

GET/api/users200

Method

Path

Status

Description

Response body

All processing happens in your browser. No data is sent to any server.

About this tool

1
Define endpoints
Add API endpoints by specifying the HTTP method, path, and response status code.
2
Configure responses
Define response bodies with static JSON or use dynamic templates for realistic data.
3
Set headers and delays
Add custom response headers and optional latency to simulate real-world conditions.
4
Export the spec
Download the mock API definition as an OpenAPI spec or a Postman collection.

Use dynamic templates like {{faker.name}} to generate realistic-looking response data.
Add deliberate delays to test how your frontend handles slow API responses.
Define error responses (400, 404, 500) alongside success responses for thorough testing.
Group related endpoints under tags to keep your mock API organized.

Build a mock backend so frontend development can proceed before the real API is ready
Create realistic API stubs for automated integration tests
Prototype an API design and share the spec with backend developers
Simulate error scenarios like timeouts and 500 errors for resilience testing

Yes. You can require API keys or Bearer tokens and return 401 responses for unauthenticated requests.

Set a delay in milliseconds for any endpoint. This is useful for testing loading states and timeout handling.

Yes. Export your mock API as a Postman collection JSON file that can be imported directly into Postman.

Updated July 11, 2026