nginx [engine x] is an HTTP and reverse proxy server, a mail proxy server, and a generic TCP/UDP proxy server, originally written by Igor Sysoev. For a long time, it has been running on many heavily loaded Russian sites including Yandex, Mail.Ru, VK, and Rambler. According to Netcraft, nginx served or proxied 25.69% busiest sites in October 2019. Here are some of the success stories: Dropbox, Netflix, Wordpress.com, FastMail.FM.