Hello Ceki, I'm glad to receive your reply. Ceki> Have you noticed that SLF4J is licensed under an MIT license? Yes, definitely. Ceki> Also, given that logback-classic natively implements the SLF4J API, Ceki> client code usually only comes into contact with SLF4J. Yes, I have fully appreciated this fact before posting to the list/blog. Ceki> Does that go to alleviate your concerns about logback's license, namely LGPL? On one account I understand that a commercial company can create derived work even from GPL works as long as the result is used only for its internal needs and distributed. From the aspect I'm okay even with GPL. But on the other account and this is why I have posted I see SLF4J as much better looking candidate for universal logging solution then Log4J. And I wish to see the vast majority of Java projects moving on and stardardising on it. This is partially selfish. As a developer I want world to settle on one tool, so that I would have less to learn. But I also want the world to standardize on the best tool. And this is where my concerns chime in. I'm really really concerned that to beat Log4J SLF4J/Logback need to beat it on all fronts. Including the license. That was the essense of my opinion: SLF4J/Logback are great and deserve to win. In order to win they need to win the hearts of Big Co-s to. And to do so they need MIT/ASL. with best regards, Anton Tagunov