MJ12bo
SEO Toolby Majestic
MJ12bot
Majestic's web crawler used for building its backlink index (Trust Flow, Citation Flow). One of the oldest and most comprehensive independent link crawlers.
Respects robots.txt
Yes
Can be blocked
Yes
Crawl-Delay support
Yes
Type
SEO Tool
Purpose
Backlink data collection for the Majestic SEO platform
SEO Impact
Blocking MJ12bot removes your site from Majestic's link metrics. This does not affect Google rankings but limits competitive analysis of your site.
User-Agent String
MJ12bot/v1.4.8
robots.txt Control
Add "User-agent: MJ12bot" with "Disallow: /" in robots.txt.
Block
User-agent: MJ12bot Disallow: /
Allow (default)
User-agent: MJ12bot Allow: /
Official Documentation
Test your robots.txt against MJ12bot
Check which paths are blocked or allowed for each user-agent