Bing
Operated by Microsoft
BingbotAbout this crawler
Bing is Microsoft's ai search indexing crawler. Indexes the page so it can be surfaced and cited in AI powered search results later. Closest in behaviour to a classic search engine crawler.
A request from Bing usually means the page is being indexed so it can be cited in AI powered search results later, not read by a person at the moment of the request.
User agent
Match on the token, not the whole header. Operators change version numbers and the surrounding text freely, so a substring match on the token is the only stable rule.
Mozilla/5.0 (compatible; Bingbot/1.0; +https://www.bing.com/webmasters/help/which-crawlers-does-bing-use-8c184ec0)
Typical shape. The exact header varies by operator and version.
Blocking it in robots.txt
User-agent: Bingbot Disallow: /
robots.txt is a request, not enforcement. Well behaved crawlers honour it; nothing stops one that does not.
Verifying a request really came from Bing
Scrapers routinely borrow a well known crawler's user agent to slip past rate limits. Checking takes three pieces.
1. User agent
What the request claims to be. It is a plain header that anyone can set, so on its own it proves nothing.
2. Request IP
The address the request actually arrived from. Your server sees it directly, and it cannot be set by the caller the way a header can.
3. Range check
The operator publishes no fixed IP list. Instead, the address a request came from is looked up in reverse DNS, the resulting hostname has to end in one of the operator’s domains, and that hostname has to resolve forward to the same address.
Approved hostname endings: search.msn.com.
This operator publishes no fixed address blocks, so there is nothing to list here. The reverse DNS check above is the documented method.
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