Back in the day, I loved a lightweight and tiny web server called Cherokee. Sadly, it's no longer popular. The last stable release was almost 10 years ago. It had a neat little admin panel built in, and it was great for both testing and production for running personal websites. You can still check out its homepage[1[ and Wikipedia[2] entry.
[1] https://cherokee-project.com/
[2] https://en.wikipedia.org/wiki/Cherokee_%28web_server%29
after that, I used Lighttpd for some time, followed by Nginx. I still have Apache around, but Nginx is now the de facto standard for me. You can still find Cherokee in some routers and embedded Linux devices. I think it's due to its size. Most distro removed those packages now, but you can still file the older Dockerfile https://github.com/managedkaos/cherokee to play around it.
@nixCraft For a super lightweight web server, don't forget the venerable old boa:
https://github.com/lanzhongheng/boa-0.94-13-ssl
@nixCraft Just make sure you keep the Clacks running.
GNU Sir Terry Prachett
Don't know what you use it for, but for a really barebone server on my internal network, I just use
busybox httpd -h /www/data -p 8080