CSR Decoder
Paste a PEM Certificate Signing Request to inspect its subject, public key, signature and SANs — entirely in your browser
Related guides
Why Your TLS Certificate Chain Breaks (and How to Fix It)
A field guide to 'unable to get local issuer certificate' and friends. What a certificate chain is, why order and intermediates matter, and how to find the broken link in a PEM bundle.
Reading a PEM Certificate: Subject, Issuer, SANs and Expiry
What the fields in a PEM certificate mean, why Subject Alternative Names matter more than the Common Name, and how to decode expiry and key usage.
How to Decode a CSR Before Sending It to a Certificate Authority
Inspect a Certificate Signing Request before you send it off. Learn what the Subject, SAN, public key and signature mean, and why modern browsers ignore CN in favor of the Subject Alternative Name.
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