MJ12bot

MJ12bot is the web crawler for Majestic, a specialist search engine company known for its backlink analysis tools. The bot's function is to map the link relationships between websites across the internet. It identifies itself in server logs with a user-agent string like Mozilla/5.0 (compatible; MJ12bot/v1.4.8; http://mj12bot.com/). MJ12bot is part of a distributed crawling system that allows Majestic to build its own comprehensive map of the internet, independent of other search engines. It is designed to be a well-behaved crawler that adheres to standard protocols.

MJ12bot is visiting your website to discover and analyze its link structure for Majestic's backlink database. It follows links it finds on other sites to reach your page and then continues to follow internal links to map your site's structure and outbound links. The frequency of its visits is determined by factors like your site's popularity and the number of inbound links it has. High-profile sites with many backlinks are likely to be crawled more often. The bot will even follow nofollow links, as they still represent a navigational path.

The purpose of MJ12bot is to build and maintain Majestic's Site Explorer, which they describe as the largest public backlink search engine index. The data it collects powers Majestic's commercial tools, which are used by SEO professionals and digital marketers to understand their backlink profiles, analyze competitors, and find link-building opportunities. For website owners, the data collected by MJ12bot can provide valuable insights into who is linking to their content and how their site is connected to the broader web.

To prevent MJ12bot from accessing your website, you can add a specific disallow rule to your robots.txt file. This is the standard method for managing access for legitimate SEO crawlers.

Add the following lines to your robots.txt file to block MJ12bot:

User-agent: MJ12bot
Disallow: /