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

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

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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%
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=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=0, report-uri="/report-expect-ct-violation"0.03%
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%