We found that across all three metrics – color, layout and AI-generated attributes – the average differences between websites peaked between 2008 and 2010 and then decreased between 2010 and 2016. Layout differences decreased the most, declining over 30% in that time frame.The graph shows website similarity of companies in the Russell 1000. Lower values mean that the sites studied were more similar, on average.Sam Goree, Author providedThese findings confirm the suspicions of web design bloggers that websites are becoming more similar. After showing this trend, we wanted to study our data to see what kinds of specific changes were causing it.You might think that these sites are simply copying each other’s code, but code similarity has actually significantly decreased over time. However, the use of software libraries has increased a lot.The graph on the left shows a decline in code similarity among Russell 1000 websites, while the graph on the right indicates an increase in library overlap.Sam Goree, Author providedLibraries feature collections of generic code for common tasks, like resizing a page for mobile devices or making a hamburger menu slide in and out. We looked at which sites had lots of libraries in common and how similar they looked. Sites built with certain libraries – Bootstrap, FontAwesome and JQuery UI – tended to look much more similar to each other. This could be because these libraries control page layout and have commonly used default options. Sites that used other libraries, like SWFObject and JQuery Tools, tended look much different, and that might be due to that fact that those libraries allow for more complex, customized pages.The changes of websites from 2005 to 2016 illustrate what’s happening.Sites with average similarity scores in 2005 tended to look less similar than those with average similarity scores in 2016.For example, in 2005, Webshots.com and Yum.com were considered relatively similar, but had somewhat different color schemes and very different layouts. While they both mostly use white, blue and black, the site on the right has a blue background.Screenshots from 2006 of Webshots.com and Yum.com.Sam Goree, Author providedTwo 2016 sites, Xfinity.com and Gilt.com, on the other hand, are even more similar: They both have a menu bar on the top and are primarily white and black with images. These pages have much less text and make better use of the higher resolution monitors that exist now.Screenshots from 2016 of Xfinity.com and Gilt.com.Sam Goree