How to query the world's largest repository of public X.509 certificates.

The Basics

Specify a field and a value in the search box. Click Search.

Format: {field_name}: {value}

Popular Fields

Subject Names

Certificates contain names of services whose identity they can verify.

Related Fields

  • parsed.subject.common_name — The primary name whose identity the certificate can verify.
  • parsed.names — All names from all name fields whose identity the certificate can verify.
  • parsed.names.raw (For exact matches)

Relevant Query Syntax

Wildcards to account for unknown characters:


Certificates are only valid for the time between the start and end dates listed in the cert.

Related Fields

  • parsed.validity.start — The date when the certificate becomes valid for use. (Unix or ISO 8601 format supported)
  • parsed.validity.end — The date when the certificate expires.
  • parsed.validity.length — The length of time in seconds that the certificate is valid.

Relevant Query Syntax

Ranges that a value can fall between. One-sided limits can also be specified:

  • [2020-10-18 TO 2021-10-20} — A value between two dates: October 18, 2020 is included. October 20, 2021 is excluded.
  • [2021-10-18 TO *] — A date after October 18, 2021.
  • [* TO 2021-10-18] — A date before October 18, 2021


Censys obtains most of its certificate records from public Certificate Transparency (CT) logs, although some are found during host scans. Censys makes this and other metadata searchable.

Related Fields

  • metadata.source — The source of the certificate record. Either scan or ct.
  • metadata.seen_in_scan — Whether or not the certificate has ever been presented by a host to a Censys scanner.
  • metadata.added_at — The timestamp indicating when the certificate record was added to the Censys repo.

Relevant Query Syntax

Booleans to combine and exclude criteria:

  • and — Returns entities matching all search criteria.
  • or — Returns entities matching any search criteria.
  • not — Returns entities that do not contain the search criteria.