HTTP response header

The Expect-CT header allows sites to opt in to reporting and/or enforcement of Certificate Transparency requirements which prevents the use of misissued certificates for that site from going unnoticed

Header usage statistics

Expect-CT response header information and usage statistics.

Websites using header Expect-CT 6,503,581
Percentage of websites that use Expect-CT header 6.57%
Total discovered header values 7,296
Header uses directives Yes
Header values are unique or random No
Most popular in the country United States of America

Expect-CT Directives (3 total)

  • enforce
  • max-age
  • report-uri

Expect-CT Directives

Expect-CT directives value information and usage statistics

Directive Share Websites count Unique Values
max-age 99.98% 6,502,232 89
report-uri 98.16% 6,383,628 1,245
enforce 1.52% 99,103 51

Connected technologies

Technologies that utilize the header

CloudFlare, category Content Delivery Networks, total 6,856,289 websites

Distribution by websites popularity

Expect-CT detection in the top websites by popularity

Top 10k sites 2,042 websites
Top 100k sites 18,905 websites
Top 1m sites 173,292 websites

Websites utilizing Expect-CT

List of websites that use Expect-CT header

Domain Country Rank Contacts
hugedomains.com United States of America 14
www.hugedomains.com United States of America 14
www.linkedin.com United States of America 19
cdnjs.cloudflare.com United States of America 20
github.com United States of America 21
maxcdn.bootstrapcdn.com United States of America 26
See full domain list
Flat price per the report, subscription is not required.

Geographical Distribution

Header usage distribution by websites across the globe.

Common header values

List of top common Expect-CT header values

Header value Value prevalence
max-age=604800, report-uri="https://report-uri.cloudflare.com/cdn-cgi/beacon/expect-ct" 97.51%
max-age=7776000, enforce 0.64%
max-age=0 0.40%
enforce, max-age=21600 0.15%
max-age=31536000, report-uri="http://csp.yahoo.com/beacon/csp?src=yahoocom-expect-ct-report-only" 0.10%
max-age=86400 0.09%
enforce, max-age=86400, report-uri="https://hpage-report.uriports.com/reports/enforce" 0.05%
max-age=86400, enforce 0.05%
enforce, max-age=31536000 0.04%
enforce, max-age=30 0.03%
enforce, max-age=300 0.03%
enforce; max-age=2592000; 0.03%
max-age=0, report-uri="/report-expect-ct-violation" 0.03%
enforce, max-age=3600 0.03%
enforce; max-age=30 0.02%
max-age=31536000, enforce 0.02%
report-uri="https://oktaexpectct.report-uri.com/r/t/ct/reportOnly", max-age=0 0.02%
enforce, max-age=86400 0.02%
enforce, max-age=43200 0.02%
enforce,max-age=86400 0.02%