How to block Majestic's MJ12bot
MJ12bot is the distributed crawler that feeds Majestic's backlink index, one of the large independent link-graph datasets used in SEO. It is a declared crawler with a documented robots.txt token and supports Crawl-delay. This page shows how to disallow it or slow it down, and links the crawler reference.
What this means
MJ12bot is operated as a distributed crawler that builds the link graph behind Majestic. Site owners often manage it the same way they manage other SEO link crawlers such as AhrefsBot and SemrushBot: either disallow it to keep your backlink data out of the dataset, or apply a Crawl-delay if you only want to reduce server load.
Because MJ12bot crawling can be distributed across many participants, requests may come from a wide range of sources, but they all carry the same robots.txt token.
How to block or slow it
To disallow MJ12bot site-wide, target its token in its own group:
User-agent: MJ12bot Disallow: /
Majestic documents that MJ12bot honours Crawl-delay, so to slow rather than block it:
User-agent: MJ12bot Crawl-delay: 10
Crawl-delay asks the crawler to wait the given number of seconds between requests. As always, robots.txt is advisory; verify in your logs that the rule changes MJ12bot's behaviour, and use a firewall rule for any client that impersonates the token without honouring the file.
- robots.txt token to target: MJ12bot
- MJ12bot is documented to support Crawl-delay
- Distributed crawling means requests can come from many sources
How it appears in analytics and logs
A request carrying the MJ12bot token is a link-graph crawl feeding Majestic's index, not a human visit. It is bot traffic. MJ12bot is distributed, so requests can arrive from many sources; the token is the stable identifier.
Diagnostic use case
Stop MJ12bot from crawling your site for Majestic's backlink index, or slow it with Crawl-delay if you only want to reduce its load.
What WebmasterID can help detect
WebmasterID classifies MJ12bot server-side as an SEO/link-graph crawler and surfaces its activity, so you can confirm whether a Disallow or Crawl-delay rule is changing its behaviour.
Common mistakes
- Assuming MJ12bot, AhrefsBot and SemrushBot share one rule — each uses its own token.
- Setting an extreme Crawl-delay and expecting instant effect; crawlers apply it gradually.
- Counting link-graph crawler hits as human traffic.
Privacy and accuracy notes
Blocking MJ12bot relies only on the request user-agent token. No human identity is involved. WebmasterID records the crawl as a bot event, separate from human analytics, and never attaches it to a visitor profile.
Related pages
- How to block MJ12bot in robots.txt
MJ12bot is the distributed crawler operated by Majestic-12 to build the Majestic backlink index. This page gives the robots.txt rule to disallow the MJ12bot token and notes that Majestic documents both a disallow and a Crawl-delay option for slowing it down.
- How to block AhrefsBot in robots.txt
AhrefsBot is the crawler Ahrefs uses to build its backlink and SEO index. This page gives the robots.txt rule to disallow it and notes that Ahrefs documents support for both robots.txt rules and the crawl-delay directive, so you can slow rather than fully block it.
- The crawl-delay directive in robots.txt
Crawl-delay is a non-standard robots.txt directive that asks a crawler to wait between requests. Support is uneven: Google does not use it and points to Search Console instead, while Bing and Yandex have historically honoured it. This page explains the directive and the safer alternatives.
- Web crawler reference
How SEO link crawlers identify themselves.
Sources and verification notes
- Majestic — MJ12bot informationDocuments the MJ12bot token and Crawl-delay support.
- Robots Exclusion Protocol (RFC 9309)
Last reviewed 2026-06-24. Facts are checked against primary/official sources where available; uncertain specifics are marked “Data not yet verified” rather than guessed.