Your files stay on your device

# X.509 certificate and CSR inspector

Paste a PEM certificate or PKCS#10 CSR and get subject, issuer, validity window, SANs, key facts, and extensions, parsed by pkijs in your tab. Nothing fetched, nothing uploaded.
PEM certificate or CSRInspectCSR PEM

- No chain validation, that needs trusted root stores and revocation data (OCSP/CRL) this offline page refuses to contact.
- “Valid now” means the validity window contains your clock. Never that anyone trusts the certificate.
- No private key handling: paste a certificate or CSR, and a CSR’s whole point is that the private key never left your machine.
Paste, drop, or type to begin. Everything stays on this device.

## More web & auth tools

- [SAML inspector](/web/saml)
- [JWK / JWKS](/web/jwk)
[All web & auth tools](/web)

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Canonical HTML: https://nutter.tools/web/certificate/
Markdown version: https://nutter.tools/web/certificate/index.md
Plain-text version: https://nutter.tools/web/certificate/index.txt
Agent index: https://nutter.tools/llms.txt