HHVM

TwistedWeb is part of the Twisted framework, providing tools for building event-driven networking applications in Python. It's used for creating scalable web servers and services.

LiteSpeed is a high-performance, lightweight web server designed for speed and scalability. It offers Apache compatibility while providing superior performance for high-traffic websites.

A modern runtime for JavaScript and TypeScript.

Centminmod is a shell script installer for quickly setting up a high-performance Nginx, PHP, MariaDB, and WordPress stack on CentOS systems.

Google Web Server (GWS) is Google's custom web server software. While not publicly available, it's optimized for Google's specific needs and high-traffic requirements.