QOS.CH Sarl (Switzerland)

QOS.ch Sarl (Switzerland) is a software design and development company based in Vouvry, Switzerland. Our company has experience building mission-critical enterprise software using the Java language.

Professional Support

Although the quality of support for various open source projects can be good, most are operated on a best-effort basis. If you require authoritative responses and guaranteed response times, then please read on.

As the founding contributors of several open source projects, namely log4j 1.x, reload4j, slf4j and logback, we offer professional support for these projects.

The base support package entails guaranteed response times. Just as importantly, it includes a review of your logging practices. Such reviews often result in considerable savings in reduced infrastructure costs. We also offer custom development services.

For more information about our support package please contact us. We will be happy to provide further details and discuss your specific needs.

Donations and sponsorships

You can also support SLF4J/logback projects via donations and sponsorship. We thank our current supporters and sponsors for their continued contributions.


Email:   sales(at)qos.ch
Postal Address:   QOS.ch Sàrl
  rue Arthur Parchet 1
  CH-1896 Vouvry (VS)

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 2024-04-11.

Project Category group:artifact usageCount percentage
SLF4J API org.slf4j:slf4j-api 67,312 69%
Commons-logging API commons-logging:commons-logging 11,980 12%
SLF4J API org.slf4j:jcl-over-slf4j 8,988 9%
LOG4J 2.x API org.apache.logging.log4j:log4j-api 8,729 9%
Total API - 96,987 100%
Project Category group:artifact usageCount percentage
LOGBACK implementation ch.qos.logback:logback-classic 27,222 48%
LOG4J 1.x implementation log4j:log4j 18,418 33%
LOG4J 2.x implementation org.apache.logging.log4j:log4j-core 10,757 19%
Total implementaion - 56,397 100%

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