libcurl
libcurl is a free, easy-to-use, thread-safe, IPv6-compatible client-side URL transfer library written in C with a stable API and ABI. It supports the same broad set of protocols as the curl command-line tool and is embedded in operating systems, applications, and developer tools across nearly every platform. Bindings are available for dozens of languages including PHP, Python, Ruby, Rust, Go, Java, .NET, and many others.