SSL Cert (PEM)

PEM format validation + DER size

v0 — limited scope

v0: PEM format validation + DER size only. Full X.509 ASN.1 decode (issuer/SAN/validity) requires OpenSSL or pkijs/forge libraries.

PEM input

✓ Valid PEM (CERTIFICATE)

Full ASN.1 decode requires OpenSSL or a heavier library:

Full parse: openssl x509 -in cert.pem -text -noout

How to use

Paste a PEM-encoded certificate or key block into the input field (beginning with -----BEGIN ...).
The tool validates the PEM structure and reports the block type, number of base64 lines, and DER byte size.
Read the success or error alert to confirm whether the PEM format is valid.
For full X.509 field decoding (issuer, SAN, validity dates), use the OpenSSL command shown in the hint.

Pasting a valid -----BEGIN CERTIFICATE----- block shows type CERTIFICATE, the base64 line count, and the DER size in bytes.
Pasting a block with a missing or mismatched footer line triggers an error alert describing the structural problem.

Verify outputs before using in production. No warranty — see Terms.