Oracle OpenJDK
OpenJDK is Oracle’s OpenJDK option. It doesn’t provide long-term support, and only offers the most recent version of the JDK without requiring a license. It is multi-platform and is available on Windows, Linux, and Mac OS. OpenJDK is TCK compliant and meets the Java SE Standard. OpenJDK’s installation is fairly straight-forward. https://openjdk.java.net/
AdoptOpenJDK
AdoptOpenJDK is another OpenJDK option. It provides long-term support for versions 8 and 11. AdoptOpenJDK offers other versions of the JDK, but they are not supported long-term. AdoptOpenJDK is multi-platform and is available on Windows, Linux, and Mac OS. AdoptOpenJDK is not currently TCK compliant. AdoptOpenJDK installation is fairly straight-forward. https://adoptopenjdk.net/releases.html
Amazon Corretto
Corretto is Amazon’s OpenJDK. It provides long-term support for versions 8 and 11. Corretto is multi-platform and can be used on Windows, Linux, and Mac OS. Corretto passes the TCK test and meets the Java SE Standard. Corretto’s installation process is minimal and straightforward. https://aws.amazon.com/corretto/
Azul Zulu
Zulu is Azul’s version of the OpenJDK. It provides long-term support for versions 6, 7, 8, and 11. It also provides other versions as well, but they are not supported long-term. Zulu is TCK compliant and meets the Java SE Standard. Zulu is multi-platform and can be used on many different platforms, including Windows, Linux, and Mac OS. Zulu’s installation process is minimal and straightforward. https://www.azul.com/downloads/zulu-community/?os=windows&architecture=x86-64-bit&package=jdk
RedHat OpenJDK
Redhat has a version of OpenJDK. It provides long-term support for versions 8 and 11. RedHat’s OpenJDK provides other versions of the JDK, but they are not supported long-term. It is multi-platform, available for Windows, and Redhat’s Linux operating system. Redhat’s OpenJDK is TCK compliant and meets the Java SE Standard. Redhat’s installation process is longer, as it requires you to create an account on their website and its Linux version is only available on its own OS, RHEL. https://developers.redhat.com/products/openjdk/download