Wikipedia
thttpd (tiny/turbo/throttling HTTP server) is an open source software web server from ACME Laboratories, designed for simplicity, a small execution footprint and speed. thttpd is single-threaded and portable: it compiles cleanly on most Unix-like operating systems, including FreeBSD, SunOS 4, Solaris 2, BSD/OS, Linux, and OSF/1. It has an executable memory size of about 50 kB. While it can be used as a simplified replacement to more feature-rich servers, it is uniquely suited to service high volume requests for static data—for example as an image hosting server. The first "t" in thttpd stands for variously tiny, turbo, or throttling.
thttpd has a bandwidth throttling feature which enables the server administrator to limit the maximum bit rate at which certain types of files may be transferred. For example, the administrator may choose to restrict the transfer of JPEG image files to at most 20 kilobytes per second. This prevents the connection from becoming saturated so that the server will still be responsive under heavy load, with the tradeoff that file transfer speed is reduced. thttpd did not support the X-Forwarded-For header
The original author considered the project "done" and stopped accepting patches around early 2004. When the Gentoo ebuild lost its maintainer and plans were made to remove it from the package tree, Anthony Basile forked the project under the name sthttpd. The current codebase consists of the original thttpd with the dozen Gentoo patches, plus a rewrite of the build system.