Most popular variants of the header value (we only show this when there's just a bunch of variants):

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. When a site enables the Expect-CT header, they are requesting that the browser check that any certificate for that site appears in public CT logs.

Reference...

We have seen 8280 websites setting the Expect-CT HTTP header and 56 unique values of this header.

  • yahoo.com max-age=31536000, report-uri="http://csp.yahoo.com/beacon/csp?src=yahoocom-expect-ct-report-only"
  • e-hentai.org max-age=604800, report-uri="https://report-uri.cloudflare.com/cdn-cgi/beacon/expect-ct"
  • search.us.com max-age=604800, report-uri="https://report-uri.cloudflare.com/cdn-cgi/beacon/expect-ct"
  • xossip.com max-age=604800, report-uri="https://report-uri.cloudflare.com/cdn-cgi/beacon/expect-ct"
  • www.basket4us.com max-age=604800, report-uri="https://report-uri.cloudflare.com/cdn-cgi/beacon/expect-ct"
  • dailyinsta.com max-age=604800, report-uri="https://report-uri.cloudflare.com/cdn-cgi/beacon/expect-ct"
  • www.workable.com max-age=604800, report-uri="https://report-uri.cloudflare.com/cdn-cgi/beacon/expect-ct"
  • internetdefenseleague.org max-age=604800, report-uri="https://report-uri.cloudflare.com/cdn-cgi/beacon/expect-ct"
  • s.yimg.com max-age=31536000, report-uri="http://csp.yahoo.com/beacon/csp?src=yahoocom-expect-ct-report-only"
  • celebuzz.com max-age=604800, report-uri="https://report-uri.cloudflare.com/cdn-cgi/beacon/expect-ct"
  • www.aftonbladet.se max-age=604800, report-uri="https://report-uri.cloudflare.com/cdn-cgi/beacon/expect-ct"
  • www.zerozero.pt max-age=604800, report-uri="https://report-uri.cloudflare.com/cdn-cgi/beacon/expect-ct"
  • www.malaysia-chronicle.com max-age=604800, report-uri="https://report-uri.cloudflare.com/cdn-cgi/beacon/expect-ct"
  • www.facebook.com max-age=86400, report-uri="https://reports.fb.com/expectct/"
  • www.irishexaminer.com max-age=604800, report-uri="https://report-uri.cloudflare.com/cdn-cgi/beacon/expect-ct"
  • www.correio24horas.com.br max-age=604800, report-uri="https://report-uri.cloudflare.com/cdn-cgi/beacon/expect-ct"
  • www.eluniversal.com.mx max-age=604800, report-uri="https://report-uri.cloudflare.com/cdn-cgi/beacon/expect-ct"
  • almogaz.com max-age=604800, report-uri="https://report-uri.cloudflare.com/cdn-cgi/beacon/expect-ct"
  • couple.me max-age=604800, report-uri="https://report-uri.cloudflare.com/cdn-cgi/beacon/expect-ct"
  • 24tv.ua max-age=604800, report-uri="https://report-uri.cloudflare.com/cdn-cgi/beacon/expect-ct"
  • www.24horas.cl max-age=604800, report-uri="https://report-uri.cloudflare.com/cdn-cgi/beacon/expect-ct"
  • www.sport24.co.za max-age=604800, report-uri="https://report-uri.cloudflare.com/cdn-cgi/beacon/expect-ct"
  • www.publico.pt max-age=604800, report-uri="https://report-uri.cloudflare.com/cdn-cgi/beacon/expect-ct"
  • www.newsit.gr max-age=604800, report-uri="https://report-uri.cloudflare.com/cdn-cgi/beacon/expect-ct"
  • www.slashfilm.com max-age=604800, report-uri="https://report-uri.cloudflare.com/cdn-cgi/beacon/expect-ct"
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