Find TLS/SSL certificates by domain, organization, serial, or fingerprint.
Type a hostname like example.com to list every certificate issued for it. Use *.example.com to include all subdomains and explore a domain’s public HTTPS certificate footprint.
Search the certificate subject by company name — PayPal, for example — to see certificates issued to an organization across all of its domains. Matching is case-insensitive and finds the query anywhere in the name, so paypal also finds “PayPal, Inc.”; queries shorter than 4 characters must match the full name exactly.
Paste a serial number (4–40 hex characters) or a SHA-256 fingerprint (64 hex) to look up one specific certificate and its complete issuance record.
64 logs from the Google and Apple CT log lists, ingested continuously — 100.0% of their 55.9 billion entries are searchable now. Monitored logs →
Server-side, on real queries: domain lookup 25-30 ms · subdomains 45-50 ms (measured 2026-09-03). API docs →
5.9 billion distinct hostnames with first-seen and last-seen dates, certificates back to 2014 — including hosts long gone from DNS.
Every hostname ever certified under a domain, with first/last seen and the live DNS verdict of our own resolver. Find subdomains →
No key needed for anonymous use with fair limits; API keys raise the quota. Machine-readable docs at llms.txt for AI agents.
Certificate Transparency (CT) is an open framework that makes the issuance of publicly trusted TLS certificates auditable: certificate authorities submit every certificate and precertificate they issue to public, append-only logs that anyone can inspect. Modern browsers reject certificates that are not logged, so the logs together form a complete public record of which certificate was issued for which domain, when, and by which CA.
ctlogs.dev continuously ingests every public CT log — operated by Google, Cloudflare, DigiCert, Let’s Encrypt, Sectigo and others — into a single searchable index of billions of certificates, precertificates and final entries alike, with new issuance appearing shortly after it is logged. See the monitored logs and our live coverage of each.
Detect rogue certificates. Certificates you didn’t request show up in the public record as soon as they are issued — a mis-issued or maliciously obtained certificate for your domain is visible here long before it is used against you.
Discover hidden subdomains. A wildcard search over *.example.com reveals subdomains that never appear in DNS enumeration or web crawls, because every HTTPS endpoint needs a certificate.
Track certificate history. Trace a certificate from its serial number or fingerprint to the issuer, validity window, SAN list and the exact CT log entries where it was seen — including the raw DER/PEM body while it is archived.