It can be used for any application and it does require the overhead of the JRE to load.
The GUI uses a tri-pane layout, with a toolbar and menu at the top, navigation pane on the left, and content viewer on the right.
The navigation pane includes searching, indexing, and a table of contents.
JavaHelp application used to come with the GNU General Public License with Classpath exception[1] However, since the source code from JavaHelp was put on GitHub for JavaEE, the source code has been re-licensed to the Common Development and Distribution License.
[1] However the source code files are still (mistakenly) under the GPLv2 with Classpath exception license[2]