AdIdxBot
Microsoft Bing operates AdIdxBot, the crawler for Bing Ads. Bing says it crawls ads and follows the websites from those ads for quality control. The Bing robots.txt tester recognises AdIdxbot as a user agent, but Bing does not state that it honors robots.txt. Bing documents no AdIdxBot-specific verification, only its generic Verify Bingbot tool and reverse DNS advice.
Mozilla/5.0 (compatible; adidxbot/2.0; +http://www.bing.com/bingbot.htm)What AdIdxBot does
Requests carry adidxbot/2.0 in the user agent, for example Mozilla/5.0 (compatible; adidxbot/2.0; +http://www.bing.com/bingbot.htm). Mobile variants use an iPhone string and a Windows Phone Lumia 530 string, each ending in the same compatible; adidxbot/2.0 token. Bing says the visits come from Bing Ads, since the bot crawls ads and follows the websites those ads point to for quality control. A site that is the destination of a Bing ad is the expected target.
Robots.txt control is thinly documented. The crawlers article says robots.txt files can tell Bing crawlers how to interact with a website, and the Bing Webmaster Tools robots.txt tester lets a site owner toggle between Bingbot and AdIdxbot to see which statement blocks a URL for which user agent. That toggle is the only place the AdIdxbot name appears in a robots.txt context, and no sentence on the source pages states that AdIdxBot honors robots.txt, so the registry records that as undocumented. Blocking it would interrupt Bing's ad quality checks on the site, per Bing's description of the bot's purpose.
Verification is generic. Bing's advice for all its crawlers is to use the Verify Bingbot tool or the verification methods it documents, which are reverse DNS to search.msn.com and the bingbot.json range file. Bing does not state whether AdIdxBot addresses appear in bingbot.json or resolve under search.msn.com, and it publishes no reverse-DNS suffix or IP list specific to AdIdxBot, so a site owner has to accept that gap.
Operator note. The documented mobile user agent variants are Mozilla/5.0 (iPhone; CPU iPhone OS 7_0 like Mac OS X) AppleWebKit/537.51.1 (KHTML, like Gecko) Version/7.0 Mobile/11A465 Safari/9537.53 (compatible; adidxbot/2.0; +http://www.bing.com/bingbot.htm) and Mozilla/5.0 (Windows Phone 8.1; ARM; Trident/7.0; Touch; rv:11.0; IEMobile/11.0; NOKIA; Lumia 530) like Gecko (compatible; adidxbot/2.0; +http://www.bing.com/bingbot.htm). The crawlers article says "Robots.txt files can be configured to tell Bing crawlers how to interact with your website", and the Bing Webmaster Tools robots.txt tester lets you "toggle between Bingbot and AdIdxbot" when testing which statement blocks a URL for which user agent. The spelling "AdIdxbot" in the tester article is the only name given for it in a robots.txt context. The documentation does not state explicitly that AdIdxBot honors robots.txt.
Controlling AdIdxBot with robots.txt
Use the token AdIdxbot in robots.txt. Microsoft Bing's documentation does not state whether this bot honors robots.txt.
User-agent: AdIdxbot
Disallow: /User-agent: AdIdxbot
Allow: /Verifying a request is really AdIdxBot
Anyone can put adidxbot/2.0 in a User-Agent header. Microsoft does not document a verification method specific to AdIdxBot. The crawlers article states for all Bing crawlers: "To ensure the IP is authentic, use the Verify Bingbot tool or learn about all verification methods we offer", those methods being reverse DNS to search.msn.com and the published list at https://www.bing.com/toolbox/bingbot.json. Whether AdIdxBot IPs are included in bingbot.json or resolve under search.msn.com is not stated.
Common questions
Does AdIdxBot obey robots.txt?
The operator's documentation does not say. Bing's robots.txt tester includes an AdIdxbot user agent toggle, and Bing says robots.txt can tell its crawlers how to interact with a site, but no page states that AdIdxBot honors robots.txt. Write a Disallow for AdIdxbot if you want to try, and check the result in the tester.
How do I verify AdIdxBot?
Bing gives no AdIdxBot-specific method. Its generic advice for Bing crawlers is the Verify Bingbot tool in Bing Webmaster Tools, reverse DNS to search.msn.com and the bingbot.json range list. Bing does not confirm that AdIdxBot IPs are in bingbot.json or resolve under search.msn.com, so treat a match as supporting evidence rather than confirmation.
Should I block AdIdxBot?
Bing says AdIdxBot crawls ads and follows the websites from those ads for quality control. Blocking it interferes with that quality check on your site. If you advertise on Bing Ads or your pages are ad destinations, that is the traffic you would be stopping; Bing documents no other purpose for the bot.
Sources
Every fact on this page was checked against Microsoft Bing's own documentation, listed below, and re-checked by a second reviewer before publication. Reviewed September 2026.
Related crawlers
This registry documents how operators describe their own bots so site owners can identify and control them. It does not publish third-party IP lists or guess at undocumented behaviour. To see how your own site responds to automated visitors, the bot detection scanner reads a URL's live response and names the protection it finds.