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The log4j software was donated to the Apache Software foundation by QOS.CH in the year 2000, over 20 years ago. We maintained the log4j 1.x framework from 2000 until 2006. In the meantime, we founded the Apache Logging top-level project and served as its first PMC chair.

In 2006, we founded the SLF4J and logback projects and continue to maintain them until this day. Cumulatively, the artifacts of these two projects are downloaded over 4 billion times per year. Given the sheer volume of users, maintaining the SLF4J and logback projects can be rather time consuming.

In 2022, we started the reload4j project with the goal of fixing critical security issues in log4j 1.x.

We wish to continue providing the most reliable, fast and flexible logging framework for Java developers. We thank our current sponsors who help us with our mission and welcome the support of new sponsors.

Prevalence of logging frameworks

Regarding the log4shell vulnerability, the prevalence of various java logging libraries puts things into perspective. Here are the relevant figures as found in mvnrepository site on 2021-12-17.

Project Category group:artifact count %
SLF4J API org.slf4j:slf4j-api 52,247 69%
Commons-logging API commons-logging:commons-logging 10,412 14%
SLF4J API org.slf4j:jcl-over-slf4j 7,546 10%
LOG4J2 API org.apache.logging.log4j:log4j-api 5,226 7%
Total API - 75,431 100%
Project Category group:artifact count %
LOGBACK implementation ch.qos.logback:logback-classic 21,770 48%
LOG4J1 implementation log4j:log4j 16,610 37%
LOG4J2 implementation org.apache.logging.log4j:log4j-core 6,974 15%
Total implementation - 45,174 100%

Notwithstanding its 48% prevalence overall (in the implementation category), no attacks have been reported against logback that we are aware of.


Founders of the log4j, reload4j, slf4j and logback projects, we are currently focusing on the latter three. We welcome your support.

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Past sponsors 39
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Meet the team

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@bekwam @dmikurube
@aajisaka @takahashikzn @andrm @americanexpress @gregorywilliams

bekwam and 9 others sponsor this goal

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