MJ12bot user agent
Operated by Majestic
MJ12bot is Majestic's distributed crawler, which builds the Majestic backlink database.
The MJ12bot bot at a glance
- MJ12bot is operated by Majestic and crawls web pages for a search engine index, and fetches pages to power a specific product feature.
- The robots.txt token for MJ12bot is MJ12bot.
- Blocking an SEO tool crawler has no effect on Google or Bing rankings.
- MJ12bot robots.txt support: Yes.
- Recommendation for Generative Engine Optimization (GEO): Your choice.
What is MJ12bot?
MJ12bot runs on many volunteer machines, so its requests come from many unrelated IP addresses.
Majestic documents MJ12bot and its robots.txt support on a dedicated site.
Should you block MJ12bot?
Blocking MJ12bot is a business decision: it protects your content but can lower how well AI products know your brand.
| Effect on search rankings | Blocking an SEO tool crawler has no effect on Google or Bing rankings. |
|---|---|
| Effect on AI visibility | No effect on AI answers. Blocking hides your pages and backlinks from that SEO tool, including from competitors who use it, and breaks your own audits in that tool. |
| Follows robots.txt | Yes |
| Recommendation | Your choice |
How to block or allow MJ12bot
Put the robots.txt rule in the file at the root of every domain and subdomain, for example https://example.com/robots.txt. The token MJ12bot is matched case-insensitively.
robots.txt: block
# Block MJ12bot
User-agent: MJ12bot
Disallow: /robots.txt: allow
# Allow MJ12bot
User-agent: MJ12bot
Allow: /robots.txt: partial
# Keep MJ12bot out of private areas only
User-agent: MJ12bot
Disallow: /wp-admin/
Disallow: /cart/
Disallow: /checkout/
Disallow: /my-account/
Allow: /Nginx
# Nginx: return 403 to MJ12bot
if ($http_user_agent ~* "(MJ12bot)") {
return 403;
}Apache
# Apache .htaccess: return 403 to MJ12bot
RewriteEngine On
RewriteCond %{HTTP_USER_AGENT} (MJ12bot) [NC]
RewriteRule .* - [F,L]Cloudflare WAF
# Cloudflare > Security > WAF > Custom rule, action: Block
(http.user_agent contains "MJ12bot")How to verify real MJ12bot traffic
Majestic publishes no IP list or reverse DNS pattern for MJ12bot, so the user agent cannot be verified. Anyone can send the same string. Rate-limit unusual volume instead of trusting the name.
How to find MJ12bot in your server logs
Search the web server access log for the token. The command below counts MJ12bot requests per URL on Nginx or Apache.
grep -i "MJ12bot" access.log | awk '{print $7}' | sort | uniq -c | sort -rn | head -20For a full report per AI bot, upload the log to the AI Log File Analyzer, a free tool by Justin Hà.
MJ12bot user agent string
The full user agent Majestic publishes for MJ12bot. Version numbers such as Chrome/W.X.Y.Z change over time, so match the token, not the whole string.
MJ12bot/v1.2.0 (http://majestic12.co.uk/bot.php?+)MJ12bot FAQ
MJ12bot identifies itself with the robots.txt token "MJ12bot". A typical request header reads: MJ12bot/v1.2.0 (http://majestic12.co.uk/bot.php?+)
Yes. Majestic states that MJ12bot follows robots.txt rules written for the "MJ12bot" token.
Blocking an SEO tool crawler has no effect on Google or Bing rankings. No effect on AI answers. Blocking hides your pages and backlinks from that SEO tool, including from competitors who use it, and breaks your own audits in that tool.
Add two lines to the robots.txt file at the root of each domain and subdomain: "User-agent: MJ12bot" followed by "Disallow: /". The token is case-insensitive. Changes can take up to 24 hours to be picked up.
Not reliably. Majestic publishes no IP list or reverse DNS pattern for MJ12bot, so anyone can send the same user agent. Rate-limit unusual volume instead of trusting the name.
Search your server access log for "MJ12bot", for example with: grep -i "MJ12bot" access.log. The AI Log File Analyzer by Justin Hà counts visits per AI bot from an uploaded log file.
Sources: Majestic crawler documentation. Last reviewed by Justin Hà.
See which of these bots actually reach your website
The AI Log File Analyzer by Justin Hà counts visits from GPTBot, ClaudeBot, PerplexityBot and other AI crawlers in your server log, for free. The GEO Technical Package sets up robots.txt, llms.txt and crawler access for AI search.
