Beast - HTTP and WebSocket built on Boost.Asio in C++11.
cpprestsdk - The C++ REST SDK is a Microsoft project for cloud-based client-server communication in native code using a modern asynchronous C++ API design. This project aims to help C++ developers connect to and interact with services.
cpr - C++ Requests: Curl for People, a spiritual port of Python Requests.
Crow - A Fast and Easy to use microframework for creating webservers (inspired by Python Flask).
dmbcs-micro-server - C++20-based JSON, HTML, text and PNGs over HTTP; simple way to embed a server into your application to provide a web-based UI.
Drogon - A C++14/17 based, high-performance HTTP application framework
oat++ - High-performance Web framework (C++11, zero-dependency).