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Yahoo-MMCrawler

Operated by Yahoo

Quick Facts

User-Agent:Yahoo-MMCrawler
Category:Search Engines
Operator:Yahoo
Safety:Safe
Blocking Impact:Critical — Blocking removes you from search results
SEO Impact Score:10/10

What is Yahoo-MMCrawler?

Yahoo-MMCrawler is used by Yahoo to crawl multimedia content such as images and videos.

Yahoo-MMCrawler is used by Yahoo to crawl multimedia content such as images and videos. Yahoo-MMCrawler is a production-grade search engine crawler operated by Yahoo. It uses a distributed crawl infrastructure that respects crawl-delay directives, follows RFC 9309 (robots.txt) spec, and processes Sitemaps to prioritise fresh content. The user-agent string Yahoo-MMCrawler must be whitelisted if your site uses rate-limiting or WAF rules. Blocking impact is Critical — Blocking removes you from search results.

What happens if you block Yahoo-MMCrawler?

⛔ **Critical Impact** — Blocking Yahoo-MMCrawler will stop Yahoo from crawling and indexing your pages. Within days or weeks you may see pages drop out of Yahoo's search index entirely, resulting in a significant loss of organic search traffic. This is the most severe possible SEO consequence. Only do this intentionally, for example if you are migrating to a different search engine or decommissioning a domain. If you accidentally blocked Yahoo-MMCrawler, remove the rule immediately and request re-indexing via Yahoo's webmaster tools.
Never block — it will remove your site from major search results.

How to block Yahoo-MMCrawler with robots.txt

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

Block completely (robots.txt)
User-agent: Yahoo-MMCrawler Disallow: /
Allow all (robots.txt)
User-agent: Yahoo-MMCrawler Allow: /
Block private only (robots.txt)
User-agent: Yahoo-MMCrawler Disallow: /private/ Disallow: /api/ Disallow: /admin/ Allow: /
Nginx server block
# Nginx: Hard-block Yahoo-MMCrawler if ($http_user_agent ~* "Yahoo\-MMCrawler") { return 403 "Bot blocked"; }
Apache .htaccess
# Apache: Hard-block Yahoo-MMCrawler SetEnvIfNoCase User-Agent "Yahoo\-MMCrawler" bad_bot Order Allow,Deny Allow from all Deny from env=bad_bot
Meta robots tag
<meta name="robots" content="noindex, nofollow">
X-Robots-Tag header
X-Robots-Tag: noindex, nofollow

Is Yahoo-MMCrawler safe to allow?

Yes, Yahoo-MMCrawler is a **safe and legitimate** crawler. It is operated by Yahoo, which publicly documents its crawler at an official URL and follows the Robots Exclusion Protocol (RFC 9309). The user-agent string Yahoo-MMCrawler is verifiable via reverse-DNS lookup on the crawling IP addresses. You can safely allow it unless you have a specific reason to block (e.g., AI training opt-out or SEO tool visibility).
Verify by reverse-DNS lookup: legitimate Yahoo-MMCrawler requests resolve to yahoo's domain.

What does Yahoo-MMCrawler do?

Understanding Yahoo-MMCrawler's purpose helps you decide whether to allow or block it.

Frequently Asked Questions

What is the official user-agent string for Yahoo-MMCrawler?
The official user-agent string for Yahoo-MMCrawler is: Yahoo-MMCrawler. 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 Yahoo-MMCrawler by performing a reverse-DNS lookup on the source IP — legitimate bots resolve back to their operator's domain.
Is Yahoo-MMCrawler safe?
Yes, Yahoo-MMCrawler is a **safe and legitimate** crawler. It is operated by Yahoo, which publicly documents its crawler at an official URL and follows the Robots Exclusion Protocol (RFC 9309). The user-agent string Yahoo-MMCrawler is verifiable via reverse-DNS lookup on the crawling IP addresses. You can safely allow it unless you have a specific reason to block (e.g., AI training opt-out or SEO tool visibility).
Will blocking Yahoo-MMCrawler hurt my SEO?
⛔ **Critical Impact** — Blocking Yahoo-MMCrawler will stop Yahoo from crawling and indexing your pages. Within days or weeks you may see pages drop out of Yahoo's search index entirely, resulting in a significant loss of organic search traffic. This is the most severe possible SEO consequence. Only do this intentionally, for example if you are migrating to a different search engine or decommissioning a domain. If you accidentally blocked Yahoo-MMCrawler, remove the rule immediately and request re-indexing via Yahoo's webmaster tools.
How do I block Yahoo-MMCrawler in robots.txt?
Add the following lines to your /robots.txt file: 
User-agent: Yahoo-MMCrawler
Disallow: /
This instructs Yahoo-MMCrawler 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 Yahoo-MMCrawler respect robots.txt?
Yes — Yahoo-MMCrawler is a well-behaved bot operated by Yahoo. It fetches and parses /robots.txt before crawling any page, following RFC 9309.
How do I verify if Yahoo-MMCrawler is crawling my site?
Search your web server access logs for the string Yahoo-MMCrawler (case-insensitive grep: grep -i "Yahoo-MMCrawler" /var/log/nginx/access.log). You can also check Google Search Console → Coverage → Crawl Stats for Googlebot variants. For Yahoo-MMCrawler specifically, filter by user-agent in your log analysis tool (GoAccess, AWStats, etc.).
What is the crawl frequency of Yahoo-MMCrawler?
Critical-impact search crawlers like Yahoo-MMCrawler typically crawl popular pages daily and less popular pages weekly. You can manage crawl rate via the crawl-delay directive or via the search console.
Can I block Yahoo-MMCrawler from specific pages only?
Yes. Instead of a global Disallow: / you can restrict Yahoo-MMCrawler to specific paths: 
User-agent: Yahoo-MMCrawler
Disallow: /private/
Disallow: /staging/
Allow: /
This allows Yahoo-MMCrawler everywhere except the listed paths. Path matching in robots.txt uses prefix matching — Disallow: /private/ blocks /private/page.html but NOT /public/private/.
How do I check if Yahoo-MMCrawler is blocked by my robots.txt?
Use Google's robots.txt Tester in Search Console, or a third-party checker to simulate a Yahoo-MMCrawler request. You can also manually check by opening https://aicrawlercheck.com/robots.txt and scanning for Yahoo-MMCrawler entries. If a block exists, immediately test it against your most important URLs using the Google Search Console URL Inspection tool.
My site is blocked by Yahoo-MMCrawler in Search Console — what do I do?
1. Open yourdomain.com/robots.txt and look for any User-agent: Yahoo-MMCrawler or User-agent: * Disallow rules covering your key pages. 2. Remove or restrict the blocking rules. 3. Validate via Google Search Console → robots.txt Tester. 4. Request re-indexing using the URL Inspection tool. 5. Wait 1-2 weeks for re-crawl. Monitor Coverage report for recovery.

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