very good.

Works well and has a pleasant interface that makes it easy to use. It's great for web test dev work, and also for bypassing poorly coded sites that hardcode a list of permitted user agents.

Good

This allowed me to sign my Progressive documents online without switching to a Windows computer

Another fake add-on that does not work at all.

Very good extension. But it is impossible to report bugs on it's website. An error is issued each time you try to report a bug. Can you put this extension on Github so we can report bugs? There is a bug when the extension's toolbar button is moved to Firefox's toolbar overflow menu. Only the left portion of the UI is displayed. Can you fix it please?

不错！做手机端测试很实用！！

good

Why this extension need it's user's Password and Username ?

Look for Permission section at review page and look for "Access your data for all websites" in this page (https://support.mozilla.org/en-US/kb/permission-request-messages-firefox-extensions)