MockNetwork is a free add-on for Chrome that enhances network debugging capabilities within DevTools. Designed specifically for developers and testers, this tool allows users to intercept, view, and modify API request responses directly in the browser. It simplifies local debugging and frontend integration by enabling the simulation of various API scenarios without altering frontend code or waiting for backend readiness.

Key features include support for fetch and XMLHttpRequest requests, customizable matching rules based on URLs, regex, or request content, and the ability to define custom status codes and response bodies. Users can easily manage interception rules through the M-Network panel in DevTools or the page sidebar. Configuration remains local, ensuring no data is uploaded to external servers, making it ideal for scenarios such as frontend integration before API availability, testing edge cases, or temporarily replicating API responses.