In the April 2013 survey we received responses from 649,072,682 sites, 17.6M more than last month. This month, market leader Apache lost 9.9M sites, or 3 percentage points of market share. A major contributor to this loss was the movement of a large affiliate referral network consisting of around 8M sites now being served by nginx. Apache is now used by just over 51% of websites, which is still substantially more than its closest competitor Microsoft IIS. IIS gained 1.95 percentage points of market share this month (an increase of 15.8M hostnames) bringing its market share to almost 20%. Meanwhile, nginx saw an overall growth of 10.6M sites this month, with the largest nginx hosting company, Hetzner Online AG, contributing an additional 1.6M sites. In terms of active sites the survey was less volatile. Apache still experienced an overall loss, however much smaller at just 288k active sites. The biggest increase came from nginx, and was unrelated to their large hostname gain described earlier, with Peer1 Networks gaining 1.5M nginx active sites.