To try the thousands of add-ons available here, download Mozilla Firefox, a fast, free way to surf the Web!Close
Welcome to Firefox Add-ons.
Choose from thousands of extra features and styles to make Firefox your own.Close
Rated 5 out of 5 stars
The highlighter addon that ís compatible with (at least) Firefox 4 and 5 can be found here:
I got this information from Netticat. Thanks!