has been included with Mozilla releases since 0.9.5, and is installable in
Netscape 6.2 or above using XPI packages. Some of its features include breakpoints, a console where debugging commands can be typed, a graphical call stack, profiling and the ability to view the code in a "pretty print" mode.
Although it is far from complete and features are still being added, as
To use it, either start Mozilla with the -venkman switch (necessary
to debug chrome code which would otherwise be loaded as part of the UI), or