The most well-known JDK and primary source of Java11 is Oracle.
OpenJDK: JDK 15, JDK 14, and JMC Azul Systems are available for use. Zing is quick and effective. OS JDK for Linux
Zulu-based Azul Systems offers products for Linux, Windows, and Mac OS X.
AIX, Linux, Windows, and numerous other OS supported by IBM J9 JDK