Last updated 8 hours ago.

What is W3C_CSS_Validator?


W3C_CSS_Validator is a developer helper operated by W3C. It's not currently known to be artificially intelligent or AI-related. If you think that's incorrect or can provide more detail about its purpose, please contact us.


Operator W3C


Developer Helper
Used by developers to test website functionality

Expected Behavior

Developer helpers generally visit websites on direct behalf of a user who is evaluating some feature or attribute. Visits can be one-off or part of a larger crawl.


Activity on Your Website

Half of your website's traffic probably comes from artificial agents, and they're becoming more intelligent every day.

Set Up Agent Analytics

Other Websites

of top websites are currently blocking W3C_CSS_Validator in some way
Learn How →

Access Control

Should I Block W3C_CSS_Validator?

Probably not. Developer helpers are normally used to optimize or find problems with your website.

Using Robots.txt

User Agent Token Description
W3C_CSS_Validator Should match instances of W3C_CSS_Validator

You can block W3C_CSS_Validator or limit its access by setting user agent token rules in your website's robots.txt.

# robots.txt
# This should block W3C_CSS_Validator

User-agent: W3C_CSS_Validator
Disallow: /

Instead of doing this manually, you can generate a robots.txt that stays up to date with the agent list automatically.

Set Up Your Robots.txt