The Web Developer extension adds a toolbar button to the browser with various web developer tools. This is the official port of the Web Developer extension for Firefox.
The best place for support is not in the reviews section below, but on the Web Developer site in the help:
Also available there are a full set of release notes:
- This extension will access your data on all websites.
- This extension will read and modify your browsing history.
- This extension will access your tabs and browsing activity.