CSR and Private Key Checker
Inspect PEM CSRs and PKCS#8 private keys: subject, signature algorithm, key type, and modulus bits or curve. Runs entirely in your browser — your key never leaves this page.
Paste a PEM certificate signing request (CSR) or an unencrypted PKCS#8 private key (BEGIN PRIVATE KEY). Parsing runs only in your browser; your private key never leaves this page or is sent to any server.
What this tool does
Paste a certificate signing request(CSR) in PEM form to see the requested subject, the signature algorithm, and the public key type (RSA modulus size or elliptic curve). When possible, the CSR's self-signature is checked. For an unencrypted PKCS#8 private key, the tool reports algorithm and size only; it does not display or export secret key bytes.
Privacy
All processing happens locally in your browser. We do not receive your PEM, CSR, or private key. Do not paste production keys on shared or untrusted devices.
For X.509 certificates (not CSRs), use the PEM Decoder.
Frequently asked questions
Is my private key sent to your servers?
No. Parsing uses Web Crypto and @peculiar/x509 only inside your browser. The key material never leaves this page.
Why is my RSA key rejected?
Legacy PEM headers like -----BEGIN RSA PRIVATE KEY----- (PKCS#1) must be converted to PKCS#8. Use openssl pkcs8 -topk8 -nocrypt -in key.pem -out key-pkcs8.pem, then paste the new file.
Where can I decode X.509 certificates?
Use the PEM Decoder tool to view certificate subject, issuer, validity, and SANs.
⭐ Rate this tool
Your feedback helps us improve
🔄 Workflow Suggestion
Try combining multiple tools for a complete workflow. For example: Notepad → Text Encryption → Save to Cloud or Date Calculator → Calendar → Countdown Timer
Related Tools & Recommendations
💡 You might also need
PEM Decoder
Decode PEM-encoded X.509 certificates. View subject, issuer, validity dates, and SANs – client-side only.
SSL Certificate Checker
Check SSL/TLS certificate validity, issuer, subject, and SANs. Paste PEM or upload .pem/.crt. Client-side only.
JWT Decoder / Encoder
Decode, encode, and verify JWT with HS256 or RS256. Explain standard claims in plain language.
📁 More Security Tools Tools
Password Generator
Generate secure, random passwords with customizable length, character types, and strength indicators
JWT Decoder / Encoder
Decode, encode, and verify JWT with HS256 or RS256. Explain standard claims in plain language.
JWT JWKS Inspector
Decode JWT, inspect claims, and verify RS256-family signatures against JWKS keys using kid matching. Client-side only.
🔗 Additional Related Tools
Send Feedback
We'd love to hear your thoughts! Your feedback helps us improve our tools and create a better experience for everyone.
Share Your Experience
Tell us what you think about this tool