User-agent lookup: which bot is this?
Paste a user-agent string from your server logs. We match it against the bots in our catalogue and show who runs the bot, what it does and how to check that a request really came from it.
Result for
Mozilla/5.0 (compatible; MJ12bot/v1.4.8; http://mj12bot.com/)
- Bot
- MJ12bot
- Operator
- Majestic
- Category
- SEO tool crawler
- Matched on
mj12bot
- Honors robots.txt?
- Yes, per Majestic
Is the request really from this bot?
- The user agent only says what the client calls itself. Anyone can send
MJ12bot, so check the requesting IP address. - We did not find an IP list or reverse-DNS method in the official source we compared on 2026-10-18, so the user agent alone cannot show that a request is genuine.
- Scripts for the check are in Fake Googlebots and PHP scanners. To allow or block the bot, see its bot page.
Questions
Can a user agent tell me whether a request is real?
No. A user-agent string is only a claim, and any client can send any string. Compare the requesting IP address with the operator's published IP ranges or, where documented, a reverse-DNS check. Our study of forged bot names has the numbers, and the crawler IP checker runs the comparison for you.
What if my user agent is not found?
The catalogue is small and checked by hand, so many bots are missing. Look for a URL or email address inside the string, which often leads to the operator's page, then check the IP address and whether the client fetched robots.txt.
Looking for the other direction? The checker shows which bots your robots.txt lets in, and the bot directory lists every bot we document. To check an address from your logs, use the crawler IP checker. To test how your own site answers these user agents, use the crawlerpeek CLI.