Oat++
Light and powerful C++ web framework for web applications
...Automatically document endpoints with Swagger-UI and OpenAPI 3.0.0. Oat++ is used for many different purposes, from building REST APIs that run on embedded devices to building microservices and highly-loaded cloud applications. Theoretically, Oat++ can be easily ported everywhere where you have threads and network stack. With an additional comparably small effort, it can be ported almost everywhere depending on how much you strip it and what would be the final binary size.