VisualVM!

The JConsole graphical user interface is a monitoring tool that complies to the Java Management Extensions (JMX) specification. JConsole uses the extensive instrumentation of the Java Virtual Machine (Java VM) to provide information about the performance and resource consumption of applications running on the Java platform.

YourKit Java Profiler is the leading profiling tool in the Java market that delivers the most innovative, powerful and smart performance analysis capabilities. YourKit Java Profiler provides extreme time savings as well as solid assurance features. Most of its features are not simply unrivaled but absolutely unique.

The Eclipse Memory Analyzer is a fast and feature-rich Java heap analyzer that helps you find memory leaks and reduce memory consumption.

JProfiler is the leading Java Profiler for profiling on the JVM. JProfiler's intuitive UI helps you resolve performance bottlenecks, pin down memory leaks and understand threading issues.

YourKit Profiler provides zero-overhead profiling for your .NET applications and makes code profiling and memory usage optimization simple and fast.