MJ12bot (Majestic): User Agent, robots.txt Rules & Safety

Q: What is the official user-agent string for MJ12bot?

The official user-agent string for MJ12bot is: MJ12bot. This is the exact string you must use in robots.txt, Nginx, Apache, or Cloudflare firewall rules to target this bot. User-agent matching in robots.txt is case-insensitive, but the string must be spelled correctly. You can verify that a request genuinely comes from MJ12bot by performing a reverse-DNS lookup on the source IP - legitimate bots resolve back to their operator's domain.

Q: How do I block MJ12bot in robots.txt?

Add the following lines to your /robots.txt file: User-agent: MJ12bot Disallow: / This instructs MJ12bot not to crawl any path on your site. The Disallow: / directive covers the entire domain including subfolders. To only block specific sections, replace / with the path (e.g., Disallow: /blog/). Note: robots.txt is publicly readable - any bot or human can inspect it at yourdomain.com/robots.txt.

Q: How do I verify if MJ12bot is crawling my site?

Search your web server access logs for the string MJ12bot (case-insensitive grep: grep -i "MJ12bot" /var/log/nginx/access.log). You can also check Google Search Console → Coverage → Crawl Stats for Googlebot variants. For MJ12bot specifically, filter by user-agent in your log analysis tool (GoAccess, AWStats, etc.).

Quick Facts

User-Agent:: MJ12bot
Category:: SEO Tools
Operator:: Majestic
Safety:: Caution
Blocking Impact:: Low - No SEO ranking impact
SEO Impact Score:: 2/10
Official docs:: mj12bot.com

What is MJ12bot?

MJ12bot is the crawler for Majestic, a link intelligence tool. It builds a map of the internet for SEO backlink analysis.

MJ12bot is the crawler for Majestic, a link intelligence tool. It builds a map of the internet for SEO backlink analysis. MJ12bot is a commercial SEO analytics crawler operated by Majestic. It builds backlink graphs, crawls for technical SEO issues, and tracks keyword rankings. The user-agent MJ12bot is well-known and respected in the SEO industry. Blocking it removes your domain from Majestic's index, preventing competitors from analysing your backlink profile via their platform. However, other Majestic users also lose visibility into links pointing TO your site - weigh this trade-off carefully.

What happens if you block MJ12bot?

✅ **No SEO Impact** - Blocking MJ12bot will not affect your search rankings. The only consequence is that your domain's data will not appear in Majestic's platform. This can be advantageous if you want to conceal your backlink profile or keyword strategy from competitors who use Majestic.

Consider blocking based on your content strategy.

How to block MJ12bot with robots.txt

<code>User-agent: MJ12bot</code> - Matching is case-insensitive. Robots.txt is fetched from the root of each subdomain separately.

Block completely (robots.txt)

User-agent: MJ12bot
Disallow: /

Allow all (robots.txt)

User-agent: MJ12bot
Allow: /

Block private only (robots.txt)

User-agent: MJ12bot
Disallow: /private/
Disallow: /api/
Disallow: /admin/
Allow: /

Nginx server block

# Nginx: Hard-block MJ12bot
if ($http_user_agent ~* "MJ12bot") {
    return 403 "Bot blocked";
}

Apache .htaccess

# Apache: Hard-block MJ12bot
SetEnvIfNoCase User-Agent "MJ12bot" bad_bot
Order Allow,Deny
Allow from all
Deny from env=bad_bot

Meta robots tag

X-Robots-Tag header

X-Robots-Tag: noindex, nofollow

Is MJ12bot safe to allow?

⚠️ **Use Caution with MJ12bot.** While operated by Majestic for stated legitimate purposes, this bot collects your content for uses you may not want to support (commercial data aggregation). It generally respects robots.txt but may revisit pages more frequently than needed. Evaluate your content strategy: if you're concerned about your data being used for these purposes, block it.

What does MJ12bot do?

Understanding MJ12bot's purpose helps you decide whether to allow or block it.

Analyzes website structure and SEO health
Tracks backlinks and referring domains
Monitors keyword rankings and competitor analysis
Crawls sites for technical SEO audits
Generates reports for SEO professionals

Frequently Asked Questions

What is the official user-agent string for MJ12bot?

The official user-agent string for MJ12bot is: MJ12bot. This is the exact string you must use in robots.txt, Nginx, Apache, or Cloudflare firewall rules to target this bot. User-agent matching in robots.txt is case-insensitive, but the string must be spelled correctly. You can verify that a request genuinely comes from MJ12bot by performing a reverse-DNS lookup on the source IP - legitimate bots resolve back to their operator's domain.

Is MJ12bot safe?

⚠️ **Use Caution with MJ12bot.** While operated by Majestic for stated legitimate purposes, this bot collects your content for uses you may not want to support (commercial data aggregation). It generally respects robots.txt but may revisit pages more frequently than needed. Evaluate your content strategy: if you're concerned about your data being used for these purposes, block it.

Will blocking MJ12bot hurt my SEO?

✅ **No SEO Impact** - Blocking MJ12bot will not affect your search rankings. The only consequence is that your domain's data will not appear in Majestic's platform. This can be advantageous if you want to conceal your backlink profile or keyword strategy from competitors who use Majestic.

How do I block MJ12bot in robots.txt?

Add the following lines to your /robots.txt file:

User-agent: MJ12bot
Disallow: /

This instructs MJ12bot not to crawl any path on your site. The Disallow: / directive covers the entire domain including subfolders. To only block specific sections, replace / with the path (e.g., Disallow: /blog/). Note: robots.txt is publicly readable - any bot or human can inspect it at yourdomain.com/robots.txt.

Does MJ12bot respect robots.txt?

⚠️ MJ12bot may not always respect robots.txt. For guaranteed blocking, combine robots.txt with server-level rules (Nginx if/return 403, Apache SetEnvIf, or Cloudflare WAF).

How do I verify if MJ12bot is crawling my site?

Search your web server access logs for the string MJ12bot (case-insensitive grep: grep -i "MJ12bot" /var/log/nginx/access.log). You can also check Google Search Console → Coverage → Crawl Stats for Googlebot variants. For MJ12bot specifically, filter by user-agent in your log analysis tool (GoAccess, AWStats, etc.).

What is the crawl frequency of MJ12bot?

Crawl frequency data for MJ12bot is not publicly documented. Monitor your logs to understand actual visit patterns.

Can I block MJ12bot from specific pages only?

Yes. Instead of a global Disallow: / you can restrict MJ12bot to specific paths:

User-agent: MJ12bot
Disallow: /private/
Disallow: /staging/
Allow: /

This allows MJ12bot everywhere except the listed paths. Path matching in robots.txt uses prefix matching - Disallow: /private/ blocks /private/page.html but NOT /public/private/.

Why would I want to block MJ12bot?

There are two main reasons to block MJ12bot: 1. **Competitive intelligence**: Majestic users (your competitors) can analyse your backlink profile, keyword rankings, and site structure. Blocking prevents this. 2. **Crawl budget**: If your site is large, SEO tool crawlers consume crawl bandwidth without contributing to search rankings. Blocking frees up server resources for search engine bots. The trade-off: you also become invisible in Majestic's backlink database, meaning links pointing TO your site from other domains won't appear in competitor reports either.