Java Tools Workbench

Open a JAR, inspect and rebuild its classes, then run or debug it in the browser.

Ready - No program loaded
Workspace
Project files 0
The workspace is empty.
In-memory browser filesystem
Loading runnable samples…

Assembly editor

Opening a .class presents an editable .j document while retaining the class as its backing file.

Open a class to edit its bytecode.

No assembly file open

Save As

A .class name assembles bytecode. A .j name preserves the assembly text, comments, and directives.

New folder

Create a directory in the browser workspace. Nested paths are created together.

For example: /src/example