CF-RAY

The CF-RAY response header is a unique ID from CloudFlare and indicates that the resource was served through CloudFlare. The CF-Cache-Status response header indicates specifically if the file was from the cache or not. If the value of CF-Cache-Status is HIT then that resource was served from CloudFlare's cache

Header usage statistics

CF-RAY response header information and usage statistics.

Websites using header CF-RAY	925,006
Percentage of websites that use CF-RAY header	8.51%
Total discovered header values	924,987
Header uses directives	No
Header values are unique or random	Yes
Most popular in the country	United States of America