API Mock Switchboard

Capture XHR/fetch responses in a side panel and switch editable mock responses per API.

API Mock Switchboard helps frontend developers capture XHR/fetch responses from the current Chrome tab and switch between editable local mock variants. Open the side panel, click Start, trigger an API request, then create a mock response tab from the captured response. Each API can keep multiple response variants with editable status, headers, and JSON/text body. Switching tabs changes which mock response is active; switching back to Original lets the real response pass through. Highlights: - Capture XHR/fetch responses from the current tab - Keep the latest original response visible in a read-only tab - Create multiple editable mock response tabs per API - Edit status code, response headers, and response body - Compare mock JSON body changes against the original response - Use a JSON editor with minimap navigation - Import and export local mock rules - Store rules locally in Chrome Privacy and safety: API Mock Switchboard only attaches Chrome debugger after the user clicks Start. Captured responses and mock rules stay local in the browser. The extension does not upload request data, response bodies, headers, rules, or browsing data to any server. Limitations: - Designed for XHR/fetch API responses - Best suited for JSON and text-like responses - Large responses may be truncated and made read-only - Chrome DevTools cannot debug the same tab while this extension is attached