The ZIP file is 664,684 bytes. Windows httpd may be used without charge for personal and educational use. At first glance, Windows httpd is an intimidating package. However, the server executable itself is only 243,216 bytes. The remaining files contain extensive documentation, images, sounds, and support software for uses more sophisticated than simple file serving.
Initial setup is straightforward.
Mac MacHTTP is an HTTP server for the Mac. This package was written by Chuck Shotton. Details are included in the documentation.