CSR Decoder
Decode and inspect Certificate Signing Requests — verify subject, SANs, key size, and signature algorithm.
Frequently Asked Questions
Understanding CSR (Certificate Signing Requests)
A Certificate Signing Request (CSR) is a PKCS#10-formatted message submitted to a Certificate Authority to apply for a digital certificate. It contains the applicant's public key, identification information (subject fields), and is signed with the corresponding private key to prove ownership.
Before submitting a CSR to a CA, it's critical to decode and verify its contents. Errors in the Common Name, Organization name, or missing SANs will result in an incorrectly issued certificate that may not work for your intended domains.
This decoder verifies the CSR's signature, extracts all subject fields, lists all SANs from the extension request, and shows the public key algorithm and size. The private key is never part of a CSR and cannot be extracted from it.