Mockiato
An open source Chrome extension built for frontend developers who need full control over network requests. It lets you intercept outgoing API calls in real time and replace them with custom mock responses, no backend required.
Open source
Response Mocking
Create mocks by specifying URL patterns (regex supported), HTTP method, response body, status code, delay, and headers. Simulate any server behavior without touching the backend.
Header Injection
Add or modify headers on outgoing requests on the fly. Perfect for testing authentication flows, CORS policies, and other header-dependent scenarios.
Zero Setup
Works instantly in the browser: no proxy servers, no config files, no CLI tools. Install and start mocking in seconds.
Open Source
Fully open source and free to use. Inspect the code, contribute features, or fork it to fit your workflow.
Gallery
A quick look at Mockiato in action: create rules, manage mocks, and test headers directly in the browser.