Rated 5 out of 5 stars

Tested on Firefox 14.0.1 and works ok.
Need some work to install, but it pays off. Best tool for xpath / xquery related jobs

See "sammingo" and "yk2000" comments for details about the install steps.

Compatibility Rated 5 out of 5 stars

Works on Firefox 13.

Rated 5 out of 5 stars

For XPath querys is the best addon for Firefox. It is simple and efficient.

In Firefox 12 works ok.