Criticalcss.com

What is Criticalcss.com?

About

Criticalcss.com bot crawls websites to generate and validate critical CSS for faster loading times. The service helps developers improve website performance by optimizing above-the-fold content delivery. You can see how often Criticalcss.com visits your website by setting up Dark Visitors agent analytics.

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.

Type

Developer Helper
Used by developers to test website functionality

Detail

Operated By Critical CSS
Last Updated 5 hours ago

Insights

Top Website Robots.txts

0%
0% of top websites are blocking Criticalcss.com
Learn How →

Country of Origin

United Kingdom
Criticalcss.com normally visits from the United Kingdom

Global Traffic

See All Global Bot & LLM Insights →

The percentage of all internet traffic coming from Developer Helpers

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Robots.txt

Should I Block Criticalcss.com?

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

How Do I Block Criticalcss.com?

⚠️ Manual Robots.txt Edits Are Not Scalable
New agents are created every day. Instead, serve a continuously updating robots.txt that blocks new agents automatically.
Set Up Automatic Robots.txt

You can block Criticalcss.com or limit its access by setting user agent token rules in your website's robots.txt. Set up Dark Visitors agent analytics to check whether it's actually following them.

User Agent String Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/79.0.3945.0 Safari/537.36 Criticalcss.com/2.0.0 
# robots.txt
# This should block Criticalcss.com

User-agent: Criticalcss.com
Disallow: /

References