SSL certificate decoder

For a certificate you already have

Unlike the other SSL tools here, this does not connect to anything - it reads a PEM-encoded certificate you paste in directly, the block of Base64 text between -----BEGIN CERTIFICATE----- and -----END CERTIFICATE-----. Useful for a certificate file sitting on disk, one from a CA's confirmation email, or one exported from a browser, before it is ever deployed anywhere.

What PEM is

Privacy-Enhanced Mail format, despite the name, became the standard plain-text container for X.509 certificates - the binary DER-encoded certificate, Base64-encoded and wrapped between header/footer lines. Most certificate files you will encounter (.pem, .crt, .cer as text) are this format.

Where it is decoded

On this server, from the pasted text, and the result is not stored - it is not sent to any third-party decoding service. Nothing about the certificate content needs to be secret for this to be safe (a certificate is, by design, public information anyone connecting to the site would see anyway), but nothing here is retained regardless.

Related tools

To inspect a certificate a live server is presenting right now, rather than one you already have, see the SSL certificate checker.