In the May 2018 survey we received responses from 1,584,940,345 sites, 217,875,435 unique domains, and 7,452,628 web-facing computers. This reflects a loss of 198 million sites, but a gain of 3.36 million domains and 65,600 web-facing computers.

nginx saw moderate growth this month, gaining 1.17 million unique domains. This has increased its market share of domains by 0.19 percentage points, even though it lost 44.2 million sites.

The nginx ecosystem has continued to evolve over the past month, with some notable software releases:

• nginx 1.14.0 was released on the 17 April, which adds HTTP/2 server push support to the nginx stable stream (the recommended release stream for production web servers). HTTP/2 server push can improve the performance of some websites by pre-emptively pushing assets to browser clients, avoiding the need for the client to explicitly make additional GET requests for assets on a page such as images, stylesheets & JavaScript.
• The first production-ready release of NGINX Unit 1.0 was released on the 12 April, ending the product's beta period. NGINX Unit is a web application server that can serve sandboxed Go, Perl, PHP, Python and Ruby applications on the same server. It is unique in allowing dynamic reloading & remote configuration via a REST API rather than individual configuration files. A bugfix release, NGINX Unit 1.1, was subsequently made available on 26 April.
• MySQL monitoring support was added to NGINX Amplify on 23 April. This commercial SaaS monitoring product from NGINX Inc. could increase the appeal of transitioning MySQL & PHP applications from Apache-based stacks to nginx-based ones.

Despite losing 59.7 million sites this month, Apache still powers sites on the largest number of unique domains. Apache is also running on 36% of the world's top 1 million websites – 12 percentage points ahead of its closest competitor, nginx.

There was also a 21% reduction of the number websites running Microsoft web server software this month, with the majority of these losses (77%) coming from hosting provider Raksmart, which lost 107 million of these sites. Despite this, the hosting provider gained 49,600 domains that point to Microsoft web servers. Many of the lost websites featured automatically generated content, and so were not counted as Active Sites.

In the April 2018 survey we received responses from 1,783,239,123 sites across 214,513,048 unique domain names and 7,387,066 web-facing computers. This reflects a gain of 12.8 million sites and 53,500 computers, but a loss of 261,000 domains.

Microsoft dominated this month's hostname growth, with 25.1 million additional hostnames bringing its leading market share up by 1.15 percentage points to 36.9%. Meanwhile, Apache lost 8.2 million sites and nginx lost 5.7 million.

Microsoft fared less well in most other metrics, however. Despite its large increase in hostnames, Microsoft's domain count fell by 1.4 million, and it also suffered a loss of 5,360 web-facing computers and 51,300 active sites. Nonetheless, its presence within the top million sites grew by 517 sites.

nginx may have lost 5.7 million hostnames, but it showed the strongest growth in some of the most important metrics. This included a gain of 46,700 web-facing computers, 3.8 million domains, and an additional 4,280 sites in the top million. The noticeable uptick in nginx-powered domains this month has increased its market share of domains by 1.81 percentage points to 22.5%, leaving it only 3.5 points behind Microsoft. nginx has demonstrated fairly consistent domain growth since this metric was introduced in 2009, and if these trends continue, it could feasibly take second place from Microsoft within a year.

Apache suffered losses in every metric this month, including a loss of 3.0 million domains and 1.1 million active sites, along with 2,840 sites within the top million. Nonetheless, it maintains a comfortable lead in every metric except hostnames, where its 25.6% market share is 11.4 points behind Microsoft's.

Some of the highest-traffic sites using Apache today include news website www.bbc.com; financial sites like www.xe.com and www.paypal.com; the Steam online gaming store at store.steampowered.com and its community forum at steamcommunity.com; and sites used by ad networks, like ads.pubmatic.com and c.betrad.com.

Apache Tomcat – the hidden backend

More than 450 million websites are currently using the Apache HTTP server, but this is not the only web server product offered by the Apache Software Foundation. The Apache Tomcat project provides an open source implementation of Java Servlet and JSP technologies, but its deployment is hard to quantify.

Tomcat is often used as a backend application server, with the Apache Tomcat Connectors project connecting it to other web-facing servers like Apache and Microsoft IIS. In many of these cases, Tomcat cannot be detected passively, although it may be possible to confirm its use during a web application security test – for example, by tricking the application into returning a Java stack trace.

Tomcat also includes its own native HTTP connector that allows it to be used as a standalone HTTP server, and these servers can be passively identified from their "Apache Tomcat" server headers. However, this is not a commonly used configuration: Only 10,300 websites exhibited the Apache Tomcat server header this month, and only 35 of these sites were ranked within the top million.

Several different versions of Apache Tomcat are available, depending which version of Java needs to be supported. Surprisingly, most Tomcat servers that are exposed directly to the internet are running Apache Tomcat 4.1.x, which has not been supported for several years. Actively maintained versions include 9.x, 8.5.x, 8.0.x and 7.x, although support for 8.0.x will end on 30 June 2018. The most recent versions of Apache Tomcat are 8.5.30 and 9.0.7, which were both released on 7 April.

Other new releases

The mainline branch of nginx has seen three new releases since last month's survey. nginx 1.13.10 was released on 20 March 2018, and added a few new features including the ngx_http_grpc_module module, which allows requests to be passed to a gRPC server. nginx 1.13.11 was subsequently released on 3 April, followed by nginx 1.13.12 on 10 April. These releases include a few bug fixes and an improved proxy protocol feature.

nginx also announced the release of njs 0.2.0 on 3 April. njs implements a subset of the JavaScript language, allowing location and variable handlers to be used in nginx's ngx_http_js_module and ngx_stream_js_module modules.

OpenLiteSpeed 1.4.31 (stable) and 1.5.0 RC3 were released on 11 April 2018. This open source server cannot be distinguished from the commercially available LiteSpeed Web Server, as both products use the same "LiteSpeed" server header. More than 12.5 million sites exhibit this header, across 13,600 web-facing computers.

Tengine 1.4.2

Nearly 28 million websites are using Taobao's nginx-based Tengine web server, but 74% are still running a version that was released several years ago, despite later releases including not just new features, but also security fixes. The most extensive user of Tengine 1.4.2 – which was released in November 2012 – is the Chinese cloud computing infrastructure service provider Aiyun Network.

Uptake of new Tengine releases is generally slow across the internet. The latest version, Tengine 2.2.2, was released on 26 January 2018, but only 262 sites are currently using it. Most of these sites are hosted by Internet Vision in Lithuania, while handfuls of other early adopters are hosted on low-cost cloud hosting platforms provided by Aliyun, DigitalOcean and Linode.

The poor uptake of newer releases could be partly caused by their lack of visibility on the Tengine website at tengine.taobao.org. The latest version that can be downloaded from the News section on the homepage is the 2.2.0 development version that was released in December 2016, followed by the 2.1.2 stable version from December 2015. Download links for the much-newer 2.2.1 and 2.2.2 releases can only be found on a separate download page.

cloudflare-nginx still lingers

Cloudflare's migration to its new cloudflare server header is not yet over, with more than 10,000 websites still using the old cloudflare-nginx header. These account for less than 0.07% of all Cloudflare sites in the survey, so the migration is very close to completion.

Cloudflare recently increased the size of its European network to 41 cities, expanding its global network to 151 cities across 74 countries. Its highest data centre is 2.6 km above sea level in the city of Bogotá, Columbia.