JSwat is a standalone, graphical Java debugger front-end, written to use the Java Platform Debugger Architecture and based on the NetBeans Platform. JSwat is open-source software and is freely available in both binary and source code form. Its features include breakpoints with conditionals; colorized source code display with code navigator; movable display panels showing threads, call stack, visible variables, and loaded classes; command interface for more advanced features; and Java-like expression evaluation, including method invocation.

URL: http://www.bluemarsh.com/java/jswat/index.html
Licence: Sun Public License