I suspect it's because ProcMon (rather than a typical debugger) uses a filter driver. medium.com/@demonia/… I'm not sure how effective the method is though. Remains to be tested.

@Vezmoq: recaf can rename classes/methods to ascii. That's usually a good first step, although sometimes doing that breaks code because some obfuscators use reflection from strings (not necessarily encrypted) and that's enough for recaf not be able to deal with the translation correctly.

They say the scripts run (only) on their servers. Some proprietary backend, of course. It's somewhat of a 2nd/3rd year in college project to write an interpreter for something as simple as that. Or even a compiler in a compiler class. How optimized it would be is another question. Possibly they translate to Java, LLVM or something else if they care more about performance.

And Bytecode Viewer, which is still maintained, might claim it's a "Debugger", but it isn't.

Most of these are far too old to be useful. The Dr. Garbage stuff doesn't work in recent Eclipses etc. JBCD is from 2003 and was probably useless even you wrote this answer, except for Java 2 or something that ancient.

@oleedd: of course it doesn't. The check is there to prevent a buffer overflow.