http://www.mirbsd.org/mksh.htm
OpenBSD switched their default shell to their own pdksh-derivative known as oksh.
https://github.com/ibara/oksh
There was an effort to (re)start ksh93 development, but AT&T halted this effort. The bugfixes from the failed effort have moved back into Korn's last release.
https://github.com/ksh93/ksh/tree/dev
http://www.mirbsd.org/mksh.htm
OpenBSD switched their default shell to their own pdksh-derivative known as oksh.
https://github.com/ibara/oksh
There was an effort to (re)start ksh93 development, but AT&T halted this effort. The bugfixes from the failed effort have moved back into Korn's last release.
https://github.com/ksh93/ksh/tree/dev