Some other libraries I have seen for http protocol based applications: https://github.com/Qihoo360/evpp - network library for developing high performance network services in TCP/UDP/HTTP protocols https://github.com/rep-movsd/see-phit - C++ HTML template engine that uses compile time HTML parsing https://github.com/boostorg/beast - HTTP and WebSocket built on Boost.Asio in C++11 https://github.com/emweb/wt - Wt, C++…
Personally, I've used: https://github.com/civetweb/civetweb
(for implementing an RFC 3161 (crypto timestamp) service.
It's a fork of https://github.com/cesanta/mongoose
(The Civetweb fork exists due to Mongoose license switch from MIT to GPLv2)