Web Servers

ApacheApache

Apache Usage Statistics · Download List of All Websites using Apache

Apache has been the most popular web server on the Internet since April 1996.

Operating Systems and Servers

UnixUnix

Unix Usage Statistics · Download List of All Websites using Unix

A *nix based operating system (undisclosed).

OpenSSLOpenSSL

OpenSSL Usage Statistics · Download List of All Websites using OpenSSL

The OpenSSL Project is a collaborative effort to develop a robust, commercial-grade, full-featured, and Open Source toolkit implementing the Secure Sockets Layer (SSL v2/v3) and Transport Layer Security (TLS v1) protocols as well as a full-strength general purpose cryptography library.