One of my current topics at work is setting up an API Gateway. We are slowly moving towards a cloud-capable environment, and having only one entry point for our growing stock of web applications can help a lot. But there was one problem, the gateway had to work with our current tech stack, which includes NTLM authentication.
We have evaluated some proxy options, namely
And for this specific problem (NTLM authentication), only NGINX and HAProxy provide a solution. And NGINX has it in their advanced bundle, while HAProxy does it out of the box with some config options enabled (see Stack Overflow question).
Therefore I will use HAProxy for a start and investigate it further. They provide a guide for Using HAProxy as an API Gateway, which is a good starting point to learn the configuration options.