CSR Decoder
Paste your Certificate Signing Request (CSR) to decode all fields — subject, organization, key type, key size, and Subject Alternative Names.
About CSR Decoder
The CSR Decoder is a free online tool that reads and displays the human-readable contents of a Certificate Signing Request (CSR). CSRs are binary-encoded files generated on your server when you initiate the SSL certificate process — their contents are not directly readable without a decoder.
Decoding a CSR lets you verify that all details are correct before submitting it to a Certificate Authority (CA) to issue your SSL certificate. A single typo in the domain name or organization field means the CA will issue a certificate with incorrect information.
How to Decode a CSR
- Copy your PEM-encoded CSR text (starts with -----BEGIN CERTIFICATE REQUEST-----)
- Paste it into the input field
- Click Decode CSR
- Review the decoded fields
Fields Revealed by Decoding
- Common Name (CN) — the primary domain being secured
- Organization (O) — your company legal name
- Organizational Unit (OU) — department
- Country (C), State (S), Locality (L) — location fields
- Subject Alternative Names — additional domains/subdomains
- Key algorithm and size — RSA 2048, EC P-256, etc.
Related tools: CSR Generator (create a new CSR), CSR Checker (verify an existing CSR). All free, no login required.