MJ12bot
Majestic •
Since 2004
Quick Actions
Official Docs
What is MJ12bot?
MJ12bot is the web crawler operated by Majestic, a UK-based company specializing in backlink analysis and link intelligence. The bot has been crawling the web since 2004, building one of the largest link databases available. Majestic's unique metrics like Trust Flow and Citation Flow are derived from MJ12bot's crawl data. The crawler operates as part of a distributed network, making it one of the most extensive web crawling operations. While some sites block MJ12bot due to its association with SEO analysis, the crawler respects robots.txt and provides valuable link data for SEO professionals.
User Agent String
Mozilla/5.0 (compatible; MJ12bot/v1.4.8; http://mj12bot.com/)
How to Control MJ12bot
Block Completely
To prevent MJ12bot from accessing your entire website, add this to your robots.txt file:
# Block MJ12bot
User-agent: MJ12bot
Disallow: /
Block Specific Directories
To restrict access to certain parts of your site while allowing others:
User-agent: MJ12bot
Disallow: /admin/
Disallow: /private/
Disallow: /wp-admin/
Allow: /public/
Set Crawl Delay
To slow down the crawl rate (note: not all bots respect this directive):
User-agent: MJ12bot
Crawl-delay: 10
How to Verify MJ12bot
Verification Method:
Check against published IP list
Check against published IP list
Learn more in the official documentation.
Detection Patterns
Multiple ways to detect MJ12bot in your application:
Basic Pattern
/MJ12bot/i
Strict Pattern
/^Mozilla/5\.0 \(compatible; MJ12bot/v1\.4\.8; http\://mj12bot\.com/\)$/
Flexible Pattern
/MJ12bot[\s\/]?[\d\.]*?/i
Vendor Match
/.*Majestic.*MJ12bot/i
Implementation Examples
// PHP Detection for MJ12bot
function detect_mj12bot() {
$user_agent = $_SERVER['HTTP_USER_AGENT'] ?? '';
$pattern = '/MJ12bot/i';
if (preg_match($pattern, $user_agent)) {
// Log the detection
error_log('MJ12bot detected from IP: ' . $_SERVER['REMOTE_ADDR']);
// Set cache headers
header('Cache-Control: public, max-age=3600');
header('X-Robots-Tag: noarchive');
// Optional: Serve cached version
if (file_exists('cache/' . md5($_SERVER['REQUEST_URI']) . '.html')) {
readfile('cache/' . md5($_SERVER['REQUEST_URI']) . '.html');
exit;
}
return true;
}
return false;
}
# Python/Flask Detection for MJ12bot
import re
from flask import request, make_response
def detect_mj12bot():
user_agent = request.headers.get('User-Agent', '')
pattern = r'MJ12bot'
if re.search(pattern, user_agent, re.IGNORECASE):
# Create response with caching
response = make_response()
response.headers['Cache-Control'] = 'public, max-age=3600'
response.headers['X-Robots-Tag'] = 'noarchive'
return True
return False
# Django Middleware
class MJ12botMiddleware:
def __init__(self, get_response):
self.get_response = get_response
def __call__(self, request):
if self.detect_bot(request):
# Handle bot traffic
pass
return self.get_response(request)
// JavaScript/Node.js Detection for MJ12bot
const express = require('express');
const app = express();
// Middleware to detect MJ12bot
function detectMJ12bot(req, res, next) {
const userAgent = req.headers['user-agent'] || '';
const pattern = /MJ12bot/i;
if (pattern.test(userAgent)) {
// Log bot detection
console.log('MJ12bot detected from IP:', req.ip);
// Set cache headers
res.set({
'Cache-Control': 'public, max-age=3600',
'X-Robots-Tag': 'noarchive'
});
// Mark request as bot
req.isBot = true;
req.botName = 'MJ12bot';
}
next();
}
app.use(detectMJ12bot);
# Apache .htaccess rules for MJ12bot
# Block completely
RewriteEngine On
RewriteCond %{HTTP_USER_AGENT} MJ12bot [NC]
RewriteRule .* - [F,L]
# Or redirect to a static version
RewriteCond %{HTTP_USER_AGENT} MJ12bot [NC]
RewriteCond %{REQUEST_URI} !^/static/
RewriteRule ^(.*)$ /static/$1 [L]
# Or set environment variable for PHP
SetEnvIfNoCase User-Agent "MJ12bot" is_bot=1
# Add cache headers for this bot
<If "%{HTTP_USER_AGENT} =~ /MJ12bot/i">
Header set Cache-Control "public, max-age=3600"
Header set X-Robots-Tag "noarchive"
</If>
# Nginx configuration for MJ12bot
# Map user agent to variable
map $http_user_agent $is_mj12bot {
default 0;
~*MJ12bot 1;
}
server {
# Block the bot completely
if ($is_mj12bot) {
return 403;
}
# Or serve cached content
location / {
if ($is_mj12bot) {
root /var/www/cached;
try_files $uri $uri.html $uri/index.html @backend;
}
try_files $uri @backend;
}
# Add headers for bot requests
location @backend {
if ($is_mj12bot) {
add_header Cache-Control "public, max-age=3600";
add_header X-Robots-Tag "noarchive";
}
proxy_pass http://backend;
}
}
Should You Block This Bot?
Recommendations based on your website type:
| Site Type | Recommendation | Reasoning |
|---|---|---|
| E-commerce | Optional | Evaluate based on bandwidth usage vs. benefits |
| Blog/News | Allow | Increases content reach and discoverability |
| SaaS Application | Block | No benefit for application interfaces; preserve resources |
| Documentation | Selective | Allow for public docs, block for internal docs |
| Corporate Site | Limit | Allow for public pages, block sensitive areas like intranets |
Advanced robots.txt Configurations
E-commerce Site Configuration
User-agent: MJ12bot
Crawl-delay: 5
Disallow: /cart/
Disallow: /checkout/
Disallow: /my-account/
Disallow: /api/
Disallow: /*?sort=
Disallow: /*?filter=
Disallow: /*&page=
Allow: /products/
Allow: /categories/
Sitemap: https://example.com/sitemap.xml
Publishing/Blog Configuration
User-agent: MJ12bot
Crawl-delay: 10
Disallow: /wp-admin/
Disallow: /drafts/
Disallow: /preview/
Disallow: /*?replytocom=
Allow: /
SaaS/Application Configuration
User-agent: MJ12bot
Disallow: /app/
Disallow: /api/
Disallow: /dashboard/
Disallow: /settings/
Allow: /
Allow: /pricing/
Allow: /features/
Allow: /docs/
Quick Reference
User Agent Match
MJ12bot
Robots.txt Name
MJ12bot
Category
seo
Respects robots.txt
Yes
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