Overview
W3C CSS Validator is a validator bot from W3C used for markup validation, accessibility testing, structured-data review, and technical page-quality checks.
Its primary user-agent pattern is W3C_CSS_Validator.
W3C CSS Validator is Verified from current authoritative identity documentation reviewed on 2026-08-07. The identity type is Official Documented.
Robots.txt behavior is not currently confirmed.
W3C CSS Validator can usually be allowed after confirming the source and monitoring request volume.
Identity
- User-Agent Pattern
-
W3C_CSS_Validator - HTTP Agent Examples
-
W3C_CSS_Validator - Robots Token
- W3C_CSS_Validator
- Identity Type
- Officially documented
- Evidence Method
- Match `W3C_CSS_Validator` to the current operator documentation and corroborate the request with operator-controlled verification signals where available; User-Agent strings alone can be spoofed.
Classification
- Type
- Validator
- Kind
- Validator
- Family
- W3C
- Purpose
- CSS validation
Behavior and handling
- Common Use
- W3C CSS Validator is used for markup validation, accessibility testing, structured-data review, and technical page-quality checks.
- Detection Notes
- W3C CSS Validator traffic is primarily detected by the `W3C_CSS_Validator` user-agent pattern. Compare source IPs, reverse DNS, request paths, and crawl cadence with W3C infrastructure before trusting the traffic.
- Respects robots.txt
- Unknown
- Spoofing Risk
- W3C CSS Validator has medium spoofing risk because user-agent strings can be copied; pair the match with DNS, IP, behavior, or operator evidence.
- Risk
- Neutral
- Recommended Handling
- Allow
Rules and controls
- Robots.txt Snippet
-
# robots.txt behavior is unconfirmed. Do not rely on this rule without verification.
Relationships
- Operator
- W3C Checked 2026-08-07
Relationships without an Evidence link are normalized from the canonical directory record. They should not be interpreted as independent proof of physical presence or request origin.