HTTPMocky

DevTools panel + content script that rewrites fetch/XHR responses

HTTPMocky is a developer tool that lets you intercept and mock HTTP requests made using fetch or XMLHttpRequest (XHR). Ideal for frontend developers, QA engineers, and anyone working with APIs, this extension helps you simulate server responses directly in the browser. Features: Create rules to match XHR or Fetch requests Override status codes and response bodies Toggle rules on/off with ease Manage everything from a custom panel inside Chrome DevTools How It Works: HTTPMocky injects lightweight code into the inspected page that wraps the native fetch and XMLHttpRequest objects. It checks each request against your defined rules and returns the mocked response or status when a match is found. Use Cases: Test frontend error handling without needing backend changes Simulate various server responses (e.g. 500 errors, empty payloads, delays) Develop offline flows or edge cases with ease changelog v1.11.2 - GA4