My current project is in D. D in my opinion, if that matters is the natural progression from c/c++ and is "the better c". I've always worked with c or c++ on backend webdevelopment as that it is lightning fast. D add's the conforts of modern programing paradigms without sacrificing this speed, and without having to learn a new syntax like you would with rust, go, etc... Any C/C++, Java, C# developer could be sat down, shown the reference material for D and be writing useful code by the end of one day.

there is vibe.d (https://code.dlang.org/packages/vibe-d) has a web framework that creates and handles http for you. However if you want to have better control and do things traditionally there is cgi_d (https://code.dlang.org/packages/cgi_d). if you want fast cgi I think there is a library for that too.

I personally prefer cgi as that it is just reading and writing to std-in and std-out and letting Apache or Nginx handle the http layer. I'm not really a fan of vibe.d because it's more than a library for web development, it's a framework. So if you Go with vibe you have to commit to the vibe way of doing web development.

I also use painlessjson so that that I can create Restful services that return json objects. As well I use mustache.d so that I can create static HTML templates to return dynamic serverside generated html.

Like most applications on the web though my current project not purly in D (while it could be), I am also using Jquery to call my Restful API to retrieve data. So it's a mixture of architecture; D on the backend, and html, javascript, css, etc... on the front end.