I'm going to give a shout out to NaviServer [0], prior called AOLServer [1]. This web server has been battle-tested and is bullet proof. When something has been used power AOL back in the day, what can you say.
OpenACS [2] is the main project of, which has existed since 1997 and that alone is highly powerful in what it can do with. Especially when coupled with TCL. It's still maintained and now supports TCL9 too!
Javascript, TCL and NaviServer (and which has it's own modules such as DNS Server, LDAP, Mail really makes an powerful tool.
If you're looking to get in to TCL and Web Development, you can really create fun with the two combined. I highly recommend that if you wish to dabble with something on the side for easy learning and plentiful features. Go take a look.
[0] https://wiki.tcl-lang.org/page/NaviServer
https://github.com/naviserver-project/naviserver
[1] https://news.ycombinator.com/item?id=35648805
https://www.linuxjournal.com/article/6164