Search Certificate Transparency logs
crtlog lets you search certificates recorded in public Certificate Transparency logs. Enter a domain, subdomain or wildcard fragment and we’ll show every certificate that includes it.
crtlog ingests both RFC 6962 and Sunlight logs from Google, Cloudflare, and Let’s Encrypt, extracts every Subject Alternative Name, and continuously resolves domains to IP addresses. Use it to monitor your own infrastructure, investigate shared hosting, or research certificates tied to a specific IP address.
Free & API usage limits
- 20 searches per day per IP for browser users.
- 1 search every 5 seconds — slow down if you see a wait message.
- Results are capped at 1,000 certificates per request; use pagination to browse more.
- Scripted access (curl, wget, python-requests) requires an API key — request a 1-month key:
- An API key raises the limit to 500 searches per day.
- Anonymous users see certificate metadata only (no raw DER).
Search by domain, subdomain, or resolved IP address. Learn more.
Off = exact match. On = also matches *.example.com and foo.example.com.
| SANs | Parent domain | Issuer | Not before | Not after | SHA-256 |
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