Nginx, created by Igor Sysoev in 2004 and headquartered in San Francisco, is the world's most widely used web server and reverse proxy, powering 33%+ of all websites.
Caddy is a modern open-source web server known for automatic HTTPS and simple configuration, created by Matthew Holt in 2015, written in Go.
The Apache Software Foundation (ASF) is the world's largest open-source software foundation. Its Apache HTTP Server was the most popular web server for decades. ASF oversees 350+ top-level projects.
WebConfig is a free open-source web server configuration management panel offering graphical management of Apache and Nginx, SSL certificates, and website configuration across major Linux distributions for budget-conscious webmasters and SMBs.
RunCloud, founded in 2016 in Malaysia, is a PHP-focused cloud server management panel supporting one-click connection to 10+ cloud platforms including DigitalOcean and AWS, with a free plan for 1 server and paid plans from about $12.5/month per server for WordPress and Laravel developers.
Kloxo is a free, open-source (AGPL v3) hosting control panel, formerly Lxadmin, installing on RHEL 8/9-family systems with about 130 one-click apps and switchable Apache/lighttpd and BIND/djbdns stacks, suited to budget virtual hosting.
KeyHelp is an open-source server control panel developed by German hosting provider Keyweb AG, free in the base version and EUR 9/month for Pro, supporting Ubuntu/Debian, 15+ languages and unlimited domains as a low-cost cPanel/Plesk alternative.