When I have no JDK environment, I want to do some things:

browse files inside a JAR decompile .class, but not upload to server edit config files (YAML, properties, JSON), and export the modified JAR inspect class structure, constant pool, bytecode

Also can use on phone. (I use it on subway.)

So I built JarPeek.

Decompiler (Vineflower) runs entirely in browser via TeaVM. No upload, no server, no install.