Bing First-Click Free Implementation
People using Bing prefer it when content they find using our search engine is accessible in full and without restrictions. As a result, we prefer to serve content in our results that is not impeded by the need to register or subscribe before our users can see the content they found through our search engine. However, in line with other search engines, we offer publishers the opportunity to implement "First Click Free" for their restricted content.
If your website contains content that is usually restricted, that is, only accessible to subscribers or registered users but you still want to be optimally represented in Bing.com results to promote your site, please follow the following guidelines to implement "First Click Free".
Allow our crawlers to crawl your site without restrictions: you can identify our crawlers by their user agent (UA) strings. The authoritative list of crawlers we use lives here.
In addition to detecting Bingbot via user-agent strings, it is possible to verify a user agent identifying itself as an official Bing crawler by using reverse a so-called Reverse DNS, forward IP lookup.
Note Important: Do not perform a "reverse DNS, forward IP lookup" on every request made to your site, as this can cause performance and availability issues. Instead, once a crawler IP address has been confirmed to be a verified Bingbot, it is safe to cache this information on the server for a considerable amount of time. Also, if you received a GET request from a Bingbot that did not pass verification, you may choose to not show the requested page in full to the IP address temporarily (or if so inclined you may block this IP address that appears to be spoofing our user agent, e.g. using HTTP Status 403 or HTTP Status 503), but you recheck after some time (e.g. 48 hours) in case this bot IP the verification simply failed.
Allow unimpeded access to the subscription or registration content to a user coming from Bing: users coming from Bing must be able to see an article they found in our search results and they clicked on without any interruption by e.g. registration or subscription screens, in-full, that is the same as a subscriber would see, without any restrictions. It is permitted to show subscription or registration screens on subsequent clicks on your website after the initial click from Bing as described in 2), but you need to allow free access to no less than five (5) articles referred from Bing per day.
To identify a user as coming from Bing, you will need to inspect the referer: header in the HTTP GET request. The simplest way is to check if the referer: header contains the domain pattern [*.bing.com*] to see if the visitor is coming from Bing and allow unimpeded access to the visited article or page.
In addition to 1 and 2, please also make sure you publish the URLs of the pages that you want indexed using XML Sitemaps (containing a comprehensive list of URLs on your site) as well as RSS feeds (containing a feed of the latest published articles). This greatly helps us discover your fresh content for crawl and indexation. See How to Submit Sitemaps to Bing for more details.
By following the guidelines above, you can have your restricted content included in the Bing index. However, implementing First Click Free does not guarantee that your content in all cases will be selected to be indexed.