YahooCacheSystem

Neutral Block: Depends Verified robots.txt: No

YahooCacheSystem caches website contents as part of the Yahoo! Search Service.

Key facts

Operator: Yahoo
Family: Yahoo
Purpose: General Crawl
User-Agent: YahooCacheSystem
Should you block it?: Depends
Verified: Yes
Respects robots.txt: No
Identity type: Unknown
Confidence: Medium
Last verified: 2026-04-01
Last checked: 2026-04-01

Bot details

Identity

User-Agent: YahooCacheSystem
robots.txt token: YahooCacheSystem
HTTP user-agent: YahooCacheSystem; YahooWebServiceClient

Ownership

Operator: Yahoo
Family: Yahoo
Type: Scraper
Purpose: General Crawl

Verification and trust

Source type: Unknown
Confidence: Medium
Last verified: 2026-04-01
Last checked: 2026-04-01
Verification: Validate the identifying user-agent or signature against the operator documentation before creating hard allow rules.
Operator URL: https://www.yahoo.com/
Source URL: https://www.yahoo.com/
Spoofing risk: User-agent strings can be spoofed. For allow-listing or low-friction rules, pair the published identifier with operator documentation or cryptographic verification when available.

Blocking and detection

Robots

User-agent: YahooCacheSystem
Disallow: /

Cloudflare

(http.user_agent contains "YahooCacheSystem")

Advanced server rules

Apache

RewriteEngine On
RewriteCond %{HTTP_USER_AGENT} YahooCacheSystem [NC]
RewriteRule ^ - [F,L]

Nginx

if ($http_user_agent ~* "YahooCacheSystem") { return 403; }

Notes

Search Service.

Known user-agent patterns: YahooCacheSystem Known user-agent strings: YahooCacheSystem; YahooWebServiceClient Robots.txt handling in the directory: no.

Operator documentation: https://www.yahoo.com/

Evidence and source

Validate the identifying user-agent or signature against the operator documentation before creating hard allow rules.
YahooCacheSystem caches website contents as part of the Yahoo! Search Service.
User-agent strings can be spoofed. For allow-listing or low-friction rules, pair the published identifier with operator documentation or cryptographic verification when available.

https://www.yahoo.com/