HtmlCompressor is a small, fast and very easy to use Java library that minifies given HTML or XML source by removing extra whitespaces, comments and other unneeded characters without breaking the content structure. As a result pages become smaller in size and load faster. A command-line version of the compressor is also available.

Tio Webpack Core

Maven HTMLCompressor Plugin allows to compress html/xml by adding a few lines to the pom file.