Open source Web servers for Linux

Apache

The Apache HTTP Server Project is an effort to develop and maintain an open-source HTTP server for modern operating systems. (Apache)

Linux - FreeBSD - Windows - MAC OS X

lighttpd

lighttpd is a web server designed to be secure, fast, standards-compliant, and flexible while being optimized for speed-critical environments. (BSD)

Cross-platform

nginx

nginx is a lightweight, high performance web server/reverse proxy and e-mail (IMAP/POP3) proxy. (BSD)

Linux - FreeBSD - Windows - MAC OS X

3 applications