I need to expand on this, but for reference, I found this on reddit - A good C++ (or C, honestly, so long as it works) HTTP server/library, and can be modified to suit:
httperf --hog --num-conns=1024 --num-calls=1 --rate=128 --server localhost --port 8080
Consider Nikto, a web server scanner which performs comprehensive tests against web servers for multiple items, including over 6700 potentially dangerous files/programs, checks for outdated versions of over 1250 servers, and version specific problems on over 270 servers. It also checks for server configuration items such as the presence of multiple index files, HTTP server options, and will attempt to identify installed web servers and software. Scan items and plugins are frequently updated and can be automatically updated.
Another tool for HTTP regression and debugging: siege which is a Debian package supplied by Joe Dog Software.