Expect-CT

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-CT6,736,887
Percentage of websites that use Expect-CT header6.67%
Total discovered header values8,013
Header uses directivesYes
Header values are unique or randomNo
Most popular in the country US

Expect-CT directives (3 total)

  • enforce
  • max-age
  • report-uri

Expect-CT Directives

Expect-CT directives value information and usage statistics

DirectiveShareWebsites countUnique Values
max-age99.98%6,735,44559
report-uri97.72%6,583,374514
enforce1.80%121,56238

Connected technologies

Technologies that utilize the header

CloudFlare, category Content Delivery Networks, total 7,049,691 websites

Distribution by websites popularity

Expect-CT detection in the top websites by popularity

Top 10k sites2,159 websites
Top 100k sites20,526 websites
Top 1m sites185,727 websites

Websites utilizing Expect-CT

List of websites that use Expect-CT header

DomainCountryRankContacts
hugedomains.com US14
www.hugedomains.com US14
www.linkedin.com US19
cdnjs.cloudflare.com US20
github.com US21
maxcdn.bootstrapcdn.com US26
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 valueValue prevalence
max-age=604800, report-uri="https://report-uri.cloudflare.com/cdn-cgi/beacon/expect-ct"97.10%
max-age=7776000, enforce0.80%
max-age=00.54%
enforce, max-age=216000.16%
max-age=31536000, report-uri="http://csp.yahoo.com/beacon/csp?src=yahoocom-expect-ct-report-only"0.10%
max-age=864000.09%
max-age=86400, enforce0.06%
enforce; max-age=36000.06%
enforce, max-age=86400, report-uri="https://hpage-report.uriports.com/reports/enforce"0.05%
enforce, max-age=315360000.04%
enforce, max-age=3000.03%
enforce; max-age=2592000;0.03%
max-age=300.03%
max-age=0, report-uri="/report-expect-ct-violation"0.03%
enforce,max-age=25920000.03%
enforce, max-age=36000.03%
enforce, max-age=864000.02%
max-age=31536000, enforce0.02%
enforce; max-age=300.02%
report-uri="https://oktaexpectct.report-uri.com/r/t/ct/reportOnly", max-age=00.02%