In the April 2007 survey we received responses from 113,658,468 sites, an increase of 3.2 million sites from last month's survey. Apache continues to be the most widely-used web server, powering more than 66.9 million sites, compared to 35.3 million sites using Microsoft server software.
This month the Web Server Survey adds public tracking of lighttpd, an open source server designed for high-performance sites that has been gaining popularity in recent months. Lighttpd is currently detected on 1.38 million sites for a 1.2% share of the web server market, well ahead of Zeus and moving up quickly on Sun. Lighttpd has a relatively small memory footprint and is optimized for a large number of parallel connections, which has made it popular on sites using applications based on AJAX or Ruby on Rails, or hosting environments for virtual private servers.
Popular sites using lighttpd as their primary server include the SourceForge developer community, the social media hub Reddit and the instant messaging service Meebo, while YouTube and Wikipedia use it to serve parts of their sites.
Sun is the sum of sites running SunONE, iPlanet-Enterprise, Netscape-Enterprise, Netscape-FastTrack, Netscape-Commerce, Netscape-Communications, Netsite-Commerce & Netsite-Communications.
Microsoft is the sum of sites running Microsoft-Internet-Information-Server, Microsoft-IIS, Microsoft-IIS-W, Microsoft-PWS-95, & Microsoft-PWS.
Platform groupings are here.