Perf4J is a performance monitoring framework for Java. It includes a simple API for performance statistics gathering, with optional Annotation support. It provides numerous analysis tools through a command line, extensions to log4j and extensions to java.util.logging, such as performance reports, graphs, and JMX integration.

Perf4J was extracted from several real world projects, and has proven itself as an indispensable tool for debugging performance problems. Perf4J has 4 active developers.