Azul sells their own high-performance Java runtime (Zing).

Taking a guess here, they probably realized there's demand among their customer base for plain OpenJDK builds with cheaper and/or more reasonable support offerings compared to Oracle's. And once you need to deliver those builds, it doesn't cost too much to let just anyone use them.

They originally built it for Microsoft to run Java apps on Azure: https://www.azul.com/successstories/microsoft/

I guess they later figured it could be more generally useful and they could sell support for it.

I had no idea Azure used it.

From the article: They wanted to offer Java on the Microsoft Azure Cloud, unencumbered by complex licensing or end-user restrictions.

What are Oracle doing that their shiny enterprise offerings just have too much baggage attached even for Microsoft?

It's openJDK but with a relatively affordable support agreement.

It's the default from sdkman I think.

Zing and Zulu are not the same. Zing is a commercial JVM that has no open source equivalent, and has a completely bespoke design from my understanding -- calling Zing a "modified openjdk" is a stretch, from what I understand (especially considering OpenJDK is GPLv2.)

Zulu is Azul's build of open-source OpenJDK, and no different than any other OpenJDK such as one from jdk.net or AdoptOpenJDK -- it doesn't have a special JIT or special GC, but you can buy a support contract for Zulu (or use it at no cost). It's basically just another OpenJDK build, as far as most people are concerned.

I was talking about Zing, yes. The parent said Zulu and I din't want to go into details. And yeah... it is more than a modified openjdk, I think we can agree and say it is based on openjdk.