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Security
Read a PEM/DER X.509 certificate’s subject, issuer, validity, and public key details.
Runs entirely in your browser, nothing is uploadedOr paste PEM text
Parsed entirely in your browser. This reads the certificate’s own fields; it does not connect to any server, check revocation, or verify the certificate chain.
Drop a PEM or DER file, or paste the PEM text. It is parsed in the page and not uploaded.
Subject, issuer, validity dates, serial number, signature algorithm, key size and any subject alternative names are read out of the certificate itself.
Expired, not yet valid, and self signed are called out, since those are the usual reasons a certificate is being looked at.
Inspect a JSON Web Key or JWKS document, field by field, without exposing private key material.
Open toolLook up a domain’s registration status, key dates, and nameservers via RDAP.
Open toolFetch a URL and check which HTTP security headers it sends, and which are missing or weak.
Open tool