I have the book PISM - Providing Internet Services on Macintosh (circa 1999), and I used run web service on classic Macs, and other services (Email, FTP, Gopher, Unix-like Talk Chat/IRC, and so on) for the community center computer room I a running then. Much of the software can run on a Mac 512K on System 6.04, though they could use a lower system but I never tried it on a lower system. Years later I also had the book Running MacHTTPD - which was a tiny version public domain version of Webstar 4.0. Throw in a few plug-ins, and it was "Kick Ass" on what one can do with an old Mac!

If it counts, I still run Webstar 5.0 on my old Duo 210 for experiments and cgi coding practice. It's been running that since 2002, and MacHTTPD since the late 1990s.