What is the best way to make an HTTP API?

Question

API

There is a service on .net.
I needed to make a simple API for my internal needs, I made it on Nancy. In principle, everything works fine, everything suits.
But now there is a need to make a public API, on which the load will be much greater, plus authentication and authorization are needed.
Question - what is the best way to do it? What do they usually do, what would you personally advise?
What IIS requires is not suitable, because I need it to work on mono as well.
Thank you.

Answer 1

As an option - ASP.NET Web API . It seems to work under Mono .

Answer 2

.net core + services stack

Answer 3

Python bottle or Python FLASK