Web site source code
Most of the curl web site is also available in a public git repository, although separate from the source code repository since it generally isn't interesting to the same people and we can maintain a different list of people that have push rights, etc.
The web site git repository is available on github at this URL: https://github.com/curl/curl-www and you can clone a copy of the web code like this:
git clone https://github.com/curl/curl-www.git
Building the web
The web site is an old custom-made setup that mostly builds static HTML files from a set of source files. The sources files are preprocessed with what is basically a souped-up C preprocessor called fcpp and a set of perl scripts. The man pages get converted to HTML with roffit. Make sure fcpp, perl, roffit, make and curl are all in your $PATH.
Once you have cloned the git repository the first time, invoke
bootstrap.sh once to get a symlink and some some initial local files setup,
and then you can build the web site locally by invoking
make in the source
Note that this doesn't make you a complete web site mirror, as some scripts and files are only available on the real actual site, but should give you enough to let you view most HTML pages locally.