jsreverse is a java decompiler that may be used from a HTML editor, without any intervention of the server other than providing the decompiler files, or from the commmand line, through nodejs.
Download the files and run make, then all the files will be contained on the web/ folder.
git clone https://github.com/kenkeiras/jsreverse/
cd jsreverse
make
# Now, we may just load web/index.html from a web browser.
Download the files and run npm install -g, the tool may be used invoking jsreverse.
git clone https://github.com/kenkeiras/jsreverse/
cd jsreverse
npm install -g