Which bot sent this user agent?
Paste a User-Agent header from your logs. The parser compares it with the 55 bots in the directory and names the one it claims to be. The string stays in your browser.
How the match works
Every bot in the bot directory has a robots.txt token, the name its operator tells site owners to use in a robots.txt rule. The parser looks for each token inside the string you paste, without regard to upper or lower case.
When one token contains another, the longest wins: a string with Googlebot-Image in it is reported as Googlebot-Image, not as Googlebot.
What a result does and does not tell you
A match tells you which bot the client says it is. It does not tell you the client is that bot. A user agent is a header the client writes, and a scraper can write Googlebot as easily as Google can.
The address the request came from is the evidence. Operators publish reverse DNS domains or address lists for their crawlers, and the crawler IP verifier checks an address against them.
No match is not a clean result either. Automation that copies a browser's user agent carries no bot name at all, and a crawler the directory does not list yet is reported as unlisted.
See which bots reach your site, and which of them are who they claim to be.
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