In the September 2016 survey we received responses from 1,285,759,146 sites and 6,118,785 web-facing computers, reflecting large gains in both metrics: 132 million additional sites, and 138,000 more computers.

Microsoft made up the majority of this month's website growth, with the largest gain of 97 million sites, although it showed only modest increases of 5,200 web-facing computers and 693,000 active sites.

Apache was responsible for most of this month's additional web-facing computers, increasing its count by 87,000 to 2.8 million (+3.2%). Similarly, nginx made a 3.0% gain of 30,000 computers. However, Microsoft's 0.3% gain was not enough to stop its share falling by half a percentage point to 25.3% as a result of the gains made by Apache and nginx.

Although nginx made a healthy gain in web-facing computers, it lost more than 5 million active sites and 5,600 sites within the top-million. 27.6% of the busiest million sites now use nginx (-0.56 pp from last month), while Apache retains its lead with a 42.5% share.

Along with nginx, all of the major web server vendors suffered losses within the top million sites, largely due to the growth of OpenResty this month. More than 10,000 of the top million sites are now using OpenResty, compared with fewer than 4,000 last month, after millions of Tumblr blogs switched from nginx. As well as tumblr.com, basecamp.com — the home of the Basecamp web-based project management tool — ranks amongst the most visited sites to use OpenResty.

Tumblr's adoption of OpenResty has caused the web server to leap up the rankings to become the seventh largest web server vendor by websites, and fifth by active sites. This month, 87% of all OpenResty sites appear under the tumblr.com domain.

Although most OpenResty sites reside under the tumblr.com domain, the number of unique domains using OpenResty also increased noticeably this month.

Switching from nginx to OpenResty is not such a paradigm shift as moving to, say, Apache or Microsoft IIS. The OpenResty web application platform is built around the standard nginx core, which offers some familiarity, as well as allowing the use of third-party nginx modules. One of the key additional features provided by OpenResty is the integration of the LuaJIT compiler and many Lua libraries – this gives scope for high performance web applications to be run completely within the bundled nginx server, where developers can take advantage of non-blocking I/O. Another web server that has gained prominence over the past year is Cowboy, a small and fast modular HTTP server written in Erlang. Optimised for low latency and low memory usage, it is currently the fifth most common web server software installed on web-facing computers that accept HTTP connections. Most of the computers used by Cowboy servers are powered by the Heroku Cloud Application Platform and hosted at Amazon Web Services.

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