Safe Data Scrapers

yacy

Operated by YaCy Community

Quick Facts

User-Agent:
yacy
Category:
Data Scrapers
Operator:
YaCy Community
Safety:
Safe
Blocking Impact:
Low - No SEO ranking impact
SEO Impact Score:
2/10

What is yacy?

YaCy is a distributed, peer-to-peer search engine. Users run their own crawler nodes.

YaCy is a distributed, peer-to-peer search engine. Users run their own crawler nodes. yacy is a data aggregation crawler. Unlike search bots or AI crawlers, its purpose is typically to collect content for private datasets, price monitoring, or research. Blocking yacy via robots.txt or at the server level has NO negative SEO impact. If you see excessive crawl volume from this bot in your logs, a hard block is recommended.

What happens if you block yacy?

✅ **Minimal Impact** - Blocking yacy has no meaningful effect on your search engine rankings or organic traffic.
Generally safe to allow; provides legitimate crawling value.

How to block yacy with robots.txt

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

Block completely (robots.txt)
User-agent: yacy Disallow: /
Allow all (robots.txt)
User-agent: yacy Allow: /
Block private only (robots.txt)
User-agent: yacy Disallow: /private/ Disallow: /api/ Disallow: /admin/ Allow: /
Nginx server block
# Nginx: Hard-block yacy if ($http_user_agent ~* "yacy") { return 403 "Bot blocked"; }
Apache .htaccess
# Apache: Hard-block yacy SetEnvIfNoCase User-Agent "yacy" 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 yacy safe to allow?

Yes, yacy is a **safe and legitimate** crawler. It is operated by YaCy Community, which publicly documents its crawler at an official URL and follows the Robots Exclusion Protocol (RFC 9309). The user-agent string yacy 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 yacy requests resolve to yacy-community's domain.

What does yacy do?

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

  • Extracts content, prices, or data from websites
  • May be used for competitive intelligence
  • Often operates without explicit permission
  • Can increase server load and bandwidth usage
  • May violate terms of service or copyright

Frequently Asked Questions

What is the official user-agent string for yacy?
The official user-agent string for yacy is: yacy. 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 yacy by performing a reverse-DNS lookup on the source IP - legitimate bots resolve back to their operator's domain.
Is yacy safe?
Yes, yacy is a **safe and legitimate** crawler. It is operated by YaCy Community, which publicly documents its crawler at an official URL and follows the Robots Exclusion Protocol (RFC 9309). The user-agent string yacy 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 yacy hurt my SEO?
✅ **Minimal Impact** - Blocking yacy has no meaningful effect on your search engine rankings or organic traffic.
How do I block yacy in robots.txt?
Add the following lines to your /robots.txt file: 
User-agent: yacy
Disallow: /
This instructs yacy 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 yacy respect robots.txt?
Yes - yacy is a well-behaved bot operated by YaCy Community. It fetches and parses /robots.txt before crawling any page, following RFC 9309.
How do I verify if yacy is crawling my site?
Search your web server access logs for the string yacy (case-insensitive grep: grep -i "yacy" /var/log/nginx/access.log). You can also check Google Search Console → Coverage → Crawl Stats for Googlebot variants. For yacy specifically, filter by user-agent in your log analysis tool (GoAccess, AWStats, etc.).
What is the crawl frequency of yacy?
yacy crawls at a moderate rate. If you notice excessive traffic in your logs, you can add a Crawl-delay directive: 
User-agent: yacy
Crawl-delay: 10
(10 second delay between requests).
Can I block yacy from specific pages only?
Yes. Instead of a global Disallow: / you can restrict yacy to specific paths: 
User-agent: yacy
Disallow: /private/
Disallow: /staging/
Allow: /
This allows yacy everywhere except the listed paths. Path matching in robots.txt uses prefix matching - Disallow: /private/ blocks /private/page.html but NOT /public/private/.
Is yacy causing high server load?
If yacy is generating excessive requests, you can: 1. Add Crawl-delay: 30 below the User-agent directive in robots.txt. 2. Rate-limit the user-agent via Nginx's limit_req_zone or Apache's mod_ratelimit. 3. Block it outright at Cloudflare WAF with rule: http.user_agent contains "yacy". 4. Use fail2ban to auto-block IPs exceeding request thresholds.

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