in reply to Decode perl cgi response in C
cURL and libcurl are C-based projects. curl will happily fetch plain text given a URL. Firefox is written mostly in C as well. Perl is written in C, and obviously is up to the task. These are examples of C projects that can send requests to a webserver, listen on a port for a response, and handle it when it comes in. Plain text is probably the easiest response to handle.
You don't have to look very far to find C programs interacting with webservers. Is that really what you were asking?