Cert Decoder is a free, user-friendly online tool designed to decode X.509 SSL/TLS certificates in PEM format. With just a few clicks, you can quickly extract essential certificate details such as the issuer, validity period, Subject Alternative Names (SAN), serial number, and fingerprint. The tool ensures maximum privacy and security by performing all processing locally within your browser—no data is ever transmitted to a server. Effortless, secure, and efficient, Cert Decoder is the perfect solution for analyzing SSL/TLS certificates.