Be explicit about uncertainty
Entry volumes are exact for these collectors; distinct certificate and domain totals are estimates. Start dates, expected error and known limitations are published alongside the figures.
Read the methodologyCT MONITORING
About
CT Monitoring provides an independent, readable view of the public Certificate Transparency ecosystem.
What we do
Our collectors follow public CT logs, verify their entries and produce aggregate measurements of the certificates and domain names observed. Coverage is sampled every two minutes, while aggregate totals refresh about every five minutes. Historical statistics retain 15-minute snapshots.
Why it matters
TLS certificates are foundational to the web. Public logging makes issuance auditable, helps surface mistakes and supports monitoring for unauthorised certificates. Aggregate statistics also reveal the extraordinary scale and rate of change of the ecosystem.
Related monitoring
The collectors also support opt-in certificate monitoring for connected services, with capacity for additional independent clients. Individuals can monitor domains directly using an email account and receive daily digests. Monitored names and certificate details are private to each account; the public statistics remain aggregate.
How we approach the data
Show collection health
Freshness and CT log coverage are visible so a number can be judged in context. Service interruptions and recoveries are recorded separately from the statistics.
Check live statusKeep public data aggregate
Only summary counts and coverage state appear in public statistics. Account watchlists and matched certificate details require sign-in.
Review privacy