Mocklet от Nikolai

Mocklet adds a panel to Firefox DevTools for turning recorded network traffic or imported HAR files into hosted HTTP mocks.

Record requests directly in DevTools or upload a HAR file, validate captured endpoints before deployment, tune matching rules for query parameters, headers, and body fields,
filter entries by resource type, and create hosted mock servers with a configurable TTL. You can also review and delete mocks from the panel. A Mocklet sign-in is required.

How to find the extension
1. Open any web page
2. Press F12 or right-click and select "Inspect"
3. Open the "Mocklet" tab