As you're probably aware, Google made mobile-friendliness a ranking signal earlier this year. Since (and even before) doing so, the company has provided webmasters with a tool that lets them check their pages to ensure that they are indeed mobile-friendly. This is something that's probably largely taken for granted as Google doesn't give you tools that let you know if you pass the test for all of its signals.
Bing has also indicated it will take mobile-friendliness into account when ranking web pages, and today announced the launch of its own mobile-friendliness tool.
"The Mobile Friendliness Test tool runs checks on all of these key factors and additionally checks for and reports on resources that are needed to analyze the page fully but that we weren’t able to crawl due to robots.txt constraints," Bing says. "This way rendering issues (as seen in the page preview) can be fixed by webmasters by updating robots.txt in such a way that Bing can accurately determine the mobile-friendliness of the sites."
"When you submit the URL of a page to be analyzed to the Mobile Friendliness Test tool, our Bing Mobile crawler fetches and renders the page, extracting important features that are used by the tool to determine how the page performs against each of the above factors," it adds. "The outcomes are then aggregated into a consolidated mobile-friendliness verdict for the page."
Bing lists the following as factors it considers with regard to mobile-friendliness: viewport and zoom control configuration; width of page content; readability of text on the page; spacing of links and other elements on page; use of incompatible plug-ins. You can get more details about each of these here.
Image via Bing