What MJ12bot does
MJ12bot is operated by Majestic-12 Ltd, a UK-based company, and maps the link relationships between websites to build the link index behind Majestic.com and its Site Explorer tool. It crawls from distributed IP addresses worldwide rather than a fixed range, so a site may occasionally be crawled by multiple MJ12bots at the same time. Per the documentation, it does not currently cache web content or personal data. It obeys robots.txt, including Crawl-Delay for up to 20 seconds and simple wildcard pattern matching in Disallow directives compatible with Yahoo's specification.
How to control MJ12bot
Target MJ12bot in your robots.txt with the MJ12bot token. Rules apply per bot, so you can allow this one while blocking others, or the reverse.
Allow MJ12bot
User-agent: MJ12bot
Allow: /Block MJ12bot
User-agent: MJ12bot
Disallow: /Because MJ12bot crawls from distributed worldwide IPs there are no published IP ranges; Majestic instead offers an optional pre-arranged ident string, sent via HTTP headers or the user agent, for verification.
How to identify MJ12bot
Temso identifies MJ12bottraffic by matching the request's User-Agent header against this pattern. User-agent strings can be spoofed, so treat a match as an indication, not proof.
MJ12botMJ12bot FAQ
What is MJ12bot?
MJ12bot is Majestic-12's distributed web crawler. It maps link relationships between websites to build the link graph that powers Majestic.com's Site Explorer.
How do I block MJ12bot?
Add a robots.txt group with 'User-agent: MJ12bot' and 'Disallow: /', or slow it down with a Crawl-Delay directive, which the bot honors for values up to 20 seconds. Because the crawler is distributed, requests come from many worldwide IPs, so robots.txt is the documented control rather than IP blocking.
About SEO & Analytics Crawlers
Crawlers behind SEO and marketing-intelligence platforms: backlink databases, site audits, rank tracking, and brand monitoring.
Blocking these has no effect on search or AI visibility. It mainly limits what third-party tools (including your competitors' tools) can see about your site.
