SSL Certificates in PEM Format

PEM is the most common format for X.509 certificates, CSRs, and cryptographic keys.

A PEM file is a text file containing one or more items in Base64 ASCII encoding, each with plain-text headers and footers (e.g., -----BEGIN CERTIFICATE----- and -----END CERTIFICATE-----).

A single PEM file could contain an end-entity certificate, a private key, or multiple certificates forming a complete chain of trust. Most certificate files are in PEM format.

PEM File Name Extensions

PEM files typically have the .crt, .pem, .cer, and .key extensions (for private keys), but you may also see them with different extensions. For example, the CA bundle file has the .ca-bundle extension.

Converting SSL Certificates

There are various reasons why you might want to convert your certificates to other formats. To learn more about converting SSL certificates, we encourage you to read our in-depth article on the subject, which provides step-by-step instructions and helpful tips for a smooth conversion process.