This minifier isn't super intelligent, but it's definitely good enough. Should probably work for all HTML, CSS, and JS. (Needs a lot more testing.)
Your job to check your text works as you want it; make sure it wasn't negatively altered.
If you have extra, unwanted spaces before/after a tag, it won't get removed, so if you want your file even smaller, fix your tags.
Use Fewer Spaces if you don't want to fix your tags. More
Extra Spaces adds an extra space before function and after else in JS. More
If you have missing semicolons, there will be errors. More
More than one script tag is not compatible with Variable/Function Renaming.
Building a minimizer is hard because accounting for all the little things in HTML, CSS, and JS takes a really long time.