Bingbot

Bing runs several crawlers, but bingbot is the main one. It requests pages, reads your robots.txt, and adds whatever it is allowed to fetch to Bing’s index. It renders pages with an “evergreen” engine that Microsoft keeps in sync with the current stable release of Microsoft Edge, and since 2022 its user-agent string reports that Edge (Chromium) version so you can see which build crawled you. It reports two user agents, desktop and mobile, so you can separate the two crawls in your logs:

Desktop: Mozilla/5.0 AppleWebKit/537.36 (KHTML, like Gecko; compatible;
         bingbot/2.0; +http://www.bing.com/bingbot.htm) Chrome/W.X.Y.Z Safari/537.36
Mobile:  Mozilla/5.0 (Linux; Android 6.0.1; Nexus 5X ...) ...
         (compatible; bingbot/2.0; +http://www.bing.com/bingbot.htm)

Bingbot’s index does not just power the classic ten blue links. It also feeds Copilot and other Bing-backed answer surfaces, which is why access control has direct AI-visibility consequences.

Verify before you trust

Bot names are trivial to spoof, so a log line that says bingbot proves nothing on its own. Microsoft recommends a reverse DNS lookup (real Bingbot resolves to a search.msn.com host) followed by a forward lookup back to the same IP, or checking the address against Bing’s published crawler IP ranges. Confirm first, then you can safely rate-limit fake bots without accidentally blocking the genuine crawler and dropping out of Bing.