Have I Been PwnedHave I Been Pwned

Have I Been Pwned Usage Statistics · Download List of All Websites using Have I Been Pwned

Domain ownership verification for haveibeenpwned provides site owners with access to reports of email addresses associated with there domain found in data breaches.

Web Hosting Providers
Email Hosting Providers

SPFSPF

SPF Usage Statistics · Download List of All Websites using SPF

The Sender Policy Framework is an open standard specifying a technical method to prevent sender address forgery.

Google Apps for BusinessGoogle Apps for Business

Google Apps for Business Usage Statistics · Download List of All Websites using Google Apps for Business

Web-based email, calendar, and documents for teams. Renamed to Google Apps for Work, but now known as G Suite from Google Cloud.

Business Email Hosting

Web Servers

nginxnginx

nginx Usage Statistics · Download List of All Websites using nginx

nginx [engine x] is a HTTP server and mail proxy server written by Igor Sysoev.

Operating Systems and Servers

UbuntuUbuntu

Ubuntu Usage Statistics · Download List of All Websites using Ubuntu

Ubuntu is a free, Debian derived Linux-based operating system, available with both community and professional support.