Like other Java enterprise tools, Tomcat has migrated from the original Java EE specification to Jakarta EE. Tomcat 9 and earlier were based on Java EE; Tomcat 10 and later are based on Jakarta EE.

Java being fully open-sourced has been a long, long time coming. While Sun open-sourced some of Java as long ago as November 2006, actually using Java in an open-source way was… troublesome. Just ask ...