MaintainJ, an Eclipse plug-in, generates runtime UML sequence and class diagrams for a given use case, helping the users to quickly understand a complex Java or J2EE application.

MaintainJ logs runtime method call trace to a file and uses that trace file to render sequence and class diagrams. MaintainJ is the tool to turn to when :
---You want to find out what exactly happens in the application when you run a use case.
---You need to quickly understand large, complex Java applications.
---You want to reduce the maintenance costs by more than 20%.

MaintainJ is different from any reverse engineering tools you have seen before.

a) Forget Static Reverse Engineering - UML diagrams from source code can take you only so far. Run a use case and generate UML sequence and class diagrams for that use case to debug and understand complex systems.
b) Debuggers are Tiresome - Debuggers help. But they are tiresome. Save the time you must spend in the debugger by first reading the runtime UML diagrams to get an overview.
c) Explore the Diagrams - MaintainJ sequence diagrams are a pleasure to read. You can expand and collapse the calls while exploring a complex sequence diagram.
d) Focus on What You Need - Only application classes (no API classes) in specified packages are shown. All loop calls and recursive calls are removed from sequence diagrams.
e) From Code or Jar - Diagrams are generated at runtime. You don't really need to have the source code.
f) Save Maintenance Costs - Development costs 10%. Maintenance costs 90%. Understanding code costs 50% of maintenance costs. Save by generating UML diagrams that help you to quickly understand code.
g) Open Source Based - MaintainJ is an Eclipse based, $100 product. Buy it or just use and blog it. Or tell us about a more useful product for those who support and maintain complex Java applications.

Check the demo videos at http://maintainj.com/head.jsp?param=demos