Nice add-on, but Rated 4 out of 5 stars

it has an annoying bug: if you leave prefix field blank, it automatically puts "www" before typed url. And if you leave suffix field blank it replaces it with "null" in address bar.

I have some often-visited communities and wanted to automate it with URL Suffix, but failed, because they have address pattern: username.site.com without "www" before username.

This review is for a previous version of the add-on (0.3.3).