Apache Log4j is a versatile, industrial-grade Java logging framework composed of an API, its implementation, and components to assist the deployment for various use cases.

You can manually download all published Log4j distributions, verify them, and see their licensing information by following the instructions in the Download page of Logging Services.

Apache Log4j 2 is an upgrade to Log4j that provides significant improvements over its predecessor, Log4j 1.x, and provides many of the improvements available in Logback while …

Apache Log4j is a versatile, industrial-grade Java logging framework composed of an API, its implementation, and components to assist the deployment for various use cases.

Log4j can be configured to poll for changes to resources (in addition to the configuration file) using the MonitorResources element of the configuration. If a change is detected in any of the …

See org.apache.log4j.chainsaw.LoggingEventFieldResolver.java for the correct names for logging event fields used when building expressions. See org.apache.log4j.chainsaw.rule package for …

GraalVM Reachability Metadata Log4j Core and all extension modules now include embedded GraalVM reachability metadata, enabling seamless generation of native images with GraalVM …

To decide which of these statements will be logged and where, users need to configure Log4j Core in one of two ways:

The Log4j Core implementation fully supports both standard and custom levels. Similarly to the Log4j API usage, custom levels must be defined in a configuration file before they can be used.

The table below contains links to the Javadoc API Documentation for the components you are most likely to use directly in code.