CSR Decoder
Paste a CSR to decode its subject and key information.
CSR Decoder quickly checks the structural validity of a Certificate Signing Request (CSR) in PEM form. It verifies that the -----BEGIN CERTIFICATE REQUEST----- block is present, that the inner base64 is intact, and that it decodes into valid DER bytes. It is ideal for catching copy-paste damage — stray line breaks or spaces — before you submit the CSR to a certificate authority.
The CSR you paste is used only for format validation and SHA-256 fingerprinting on the server and is never stored. To fully read fields like the subject (CN) and SANs, the most accurate approach is to runopenssl req -in csr.pem -noout -text locally. This tool focuses on a lightweight "is the format correct" check right before submission. Once the certificate is issued, expand it with the SSL Certificate Decoder, and after installing it on a server run a live check with the SSL Certificate Checker.
What is a CSR
A CSR is the request data you submit to a certificate authority to obtain an SSL/TLS certificate. It contains your public key and subject information (domain, organization, etc.) and is signed with your private key, usually encoded as Base64 PEM text. The private key itself is never part of the CSR, so it is safe to share.
Create and inspect a CSR with openssl
- Generate a new key + CSR:
openssl req -new -newkey rsa:2048 -nodes -keyout domain.key -out domain.csr - View CSR contents:
openssl req -in domain.csr -noout -text - Verify the CSR signature:
openssl req -in domain.csr -noout -verify - Show subject only:
openssl req -in domain.csr -noout -subject
Pre-submission checklist
- You pasted the entire PEM including the BEGIN/END lines
- No stray spaces or line breaks broke the base64 body
- The key is at least 2048-bit RSA or ECDSA P-256 or stronger
- The Common Name and SANs contain exactly the domains you need