PocketMocker

PocketMocker is an in-page HTTP controller and mocking tool for frontend developers that lets you intercept, modify, or simulate API responses directly in a web application without requiring backend changes or separate mock servers. Running inside the browser, it provides a floating control panel that automatically captures outgoing requests and allows developers to override responses, simulate errors or latency, or test edge cases on the fly. This makes building, debugging, and verifying user interfaces significantly faster because developers can instantly see how their UI reacts to different API conditions without switching contexts. Pocket-Mocker also supports team collaboration through configuration plugins and shared rule sets. Its UI and manual are designed to be intuitive, so even those new to API mocking can quickly catch up. For complex applications with many third-party endpoints or unpredictable backends, Pocket-Mocker removes friction in development and testing cycles.