HHVM

Apache Traffic Server is an open-source caching proxy server. It offers high-performance caching, proxying, and load balancing capabilities for web traffic management.

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.

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

A modern runtime for JavaScript and TypeScript.

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.