is a plug-in for Notepad++
You can check out the readme file
for more information about it.
Due to various reasons, I probably won't be updating this plugin anymore. You can read more here.
If you encounter a problem with it, or you wish to request new features, you can do so by creating a ticket here, at SourceForge, or on SF's HTMLTag forum.
Note that on this site, you can login anonymously; on SF, you have to register first. Then again, there's so much useful stuff on SourceForge that you’re probably already registered there anyway. :-)
The latest version of the plugin can be downloaded from this site:
You can also download most of the previous versions.