MJ12 Bot

Operator

Majestic

Type

Search bot

Official page

mj12bot.com

robots.txt token

MJ12bot

Follows robots.txt

Yes, according to Majestic.

In Vireo

Excluded, reported under SEO tools

What it does

Majestic's distributed crawler. It maps links between websites for Majestic's backlink index.

Crawled data (currently only a web graph of links) is added to the largest public backlinks search engine index that we maintain as a dedicated tool called Site Explorer.

Majestic

User agent

Requests from MJ12 Bot carry a user agent like this:

Mozilla/5.0 (compatible; MJ12bot/v1.4.4; http://www.majestic12.co.uk/bot.php?+)

Device Detector identifies it with this pattern (a case-insensitive regular expression):

MJ12bot

Anyone can put any name in a user agent. Where the operator publishes IP ranges, checking the request's address against them is the way to confirm a visit is genuine.

How to block or allow MJ12 Bot

Add a group for its token to the robots.txt file at the root of your site. To keep it out of the whole site:

User-agent: MJ12bot
Disallow: /

To let it crawl everything, use an empty Disallow: or Allow: / instead. WordPress serves a virtual robots.txt that many SEO plugins let you edit. A real robots.txt file uploaded to the site root takes its place.

User-agent: MJ12bot Disallow: /

Majestic

MJ12bot adheres to the robots.txt standard.

Majestic

robots.txt is a request, so it only works on crawlers that honour it. A bot that ignores it has to be blocked at the server or firewall, by user agent or IP address.

Worth knowing

It runs on volunteers' machines, so there's no IP list. If it can't fetch robots.txt it assumes it may crawl, though a 403 on robots.txt counts as a full disallow.

Please do not block our bot via IP in htaccess - we do not use any consecutive IP blocks as we are a community based distributed crawler.

Majestic

How Vireo counts MJ12 Bot

Vireo keeps requests from MJ12 Bot out of your pageviews and visitors and counts them on its bot report under SEO tools, so you can see how much it left out rather than wonder why your server logs show more traffic.

Checked by running Vireo Analytics' own bot filter over MJ12 Bot's user agents.

Sources

• Majestic: crawler documentation (checked October 2026)
• MJ12 Bot information page (majestic12.co.uk)
• Matomo Device Detector, bots.yml (LGPL-3.0)