About 82% of the Alexa 100 top sites use some form of server-side mobile device detection to serve content on their main website entry point. As you descend from the top 10 to the top 25 and top 100 sites the percentage of sites using server-side detection falls from 100% to 96% to 82%. This is an interesting fact given that all the recent discussion in the blogosphere is of responsive design using client-side techniques such as media queries. You can read more about these techniques in our article describing current mobile adaptation techniques.
How exactly did I measure this? I took five devices and visited the main entry points for the latest Alexa Top Global Sites list. I compared the size of the returned HTML document for each of the devices in question to see if server-side redirection and/or adaptation was being used. To avoid having to actually view the resulting page from each device I used the page byte size as a proxy measurement: if different user-agent strings resulted in significantly different returned HTML byte size for the same URL, I count this as server-side device detection at work. Where known, I used the full set of HTTP headers for each device in addition to the correct user-agent string.
|Server-Side Mobile Web Adaptation|
|Top 10 Sites||Top 25 Sites||Top 100 Sites|
|Extensive (greater than 3 versions)||80%||88%||74%|
|Any adaptation at all||100%||96%||82%|
Google is the star performer, fine-tuning all of its properties in all territories. The most notable non-adapting sites in the top 25 are Apple and Craigslist (to be fair to Craigslist their site is quite efficient thanks to its spare use of images).
Mobile Devices Used
|Data Center||Policy & Regulation|
|DNS Security||Regional Registries|
|Domain Names||Registry Services|
|Intellectual Property||Top-Level Domains|
|Internet of Things||Web|
|Internet Protocol||White Space|
Afilias - Mobile & Web Services
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