🔐 CSR Decoder

About CSR Decoder

The CSR Decoder is a professional security tool for decoding and analyzing Certificate Signing Requests (CSRs) used in SSL/TLS certificate generation. Instantly extract all information from your CSR including domain names, organization details, public key information, signature algorithms, and key usage extensions. Essential for system administrators, security engineers, and DevOps professionals to verify CSR content, troubleshoot SSL certificates, or audit security configurations.

Features

• Instant Decoding: Decode CSR files directly in your browser in seconds
• Subject Information: View Common Name (CN), Organization (O), Organizational Unit (OU), Country (C), State/Province (ST), and Locality (L)
• Public Key Details: Extract key algorithm, size, and modulus information
• Signature Algorithm: Identify the CSR's signing algorithm
• Subject Alternative Names (SAN): Display all SAN entries for multi-domain certificates
• Key Usage Extensions: View intended key usages and extended usages
• Validation Status: Verify CSR format and structural integrity
• Sample CSR: Load example CSRs to test and understand the format
• Copy All: Copy decoded information to clipboard in one click
• Client-Side Processing: All decoding occurs locally; no data is sent to servers
• No File Upload Needed: Simply paste CSR text into the tool
• Error Reporting: Detailed error messages and troubleshooting hints

How to Use

• Step 1: Copy your CSR text including BEGIN/END markers
• Step 2: Paste CSR into the text area
• Step 3: Click "Decode CSR" to extract information
• Step 4: Review subject info, public key details, and extensions
• Step 5: Verify the Common Name matches your domain
• Step 6: Check organization details for accuracy
• Step 7: Use "Copy All" to save information
• Step 8: Click "Load Sample" if you don’t have a CSR

Understanding CSR Components

• Common Name (CN): Fully qualified domain name (FQDN), e.g., "www.example.com"
• Organization (O): Legal organization or company name
• Organizational Unit (OU): Department or division
• Country (C): Two-letter ISO country code
• State/Province (ST): State, province, or region
• Locality (L): City
• SAN: Additional domains/subdomains covered
• Public Key: Cryptographic key included in certificate
• Key Size: Length in bits (2048/4096 typical)
• Signature Algorithm: Algorithm used to sign the CSR (e.g., SHA-256 with RSA)

Common Use Cases

• Verify CSR before submission to a Certificate Authority
• Check Common Name matches the intended domain
• Ensure organization details for EV/OV certificates are accurate
• Confirm SAN entries for multi-domain certificates
• Validate key size and security compliance
• Troubleshoot SSL certificate requests
• Audit CSR security parameters
• Verify CSR for certificate renewals
• Check wildcard certificate formatting (*.example.com)
• Use in DevOps automation workflows for certificate management
• Learning CSR structure and SSL/TLS concepts
• Extract CSR information for documentation purposes

Privacy & Security

• All decoding occurs client-side in your browser
• No CSR data is transmitted or stored on servers
• CSRs contain only public information; private keys are never exposed
• Use HTTPS to access the tool securely