X.509 Certificate Inspector & Exporter
Zero EgressInspect, validate, and convert SSL/TLS certificates client-side. Convert between PEM, binary DER, Public Key SPKI, and JSON with zero data egress.
Drop Certificate (.crt, .pem, .der, .cer) or click to browse
Supports ASCII PEM & Binary DER • Decoded entirely in-browser
X.509 Certificate & PKI Inspector with Cryptographic Sanity Checks
Inspect, parse, and validate X.509 SSL/TLS certificates and CSRs entirely inside your browser. Analyze validity periods, SANs, key sizes, digital signatures, and extension constraints without sharing sensitive cryptographic material.
How Client-Side Processing Works
Every step executes within your browser runtime without network calls or cloud storage.
- 1PEM or DER encoded certificates are decoded into raw binary ASN.1 structures locally.
- 2The parser extracts Subject, Issuer, Serial Number, Validity Ranges, Subject Alternative Names (SANs), and Key Usages.
- 3Web Crypto computes SHA-256 and SHA-1 fingerprints in memory for cryptographic verification.
- 4Validity timelines and expiration warnings calculate based on current system time.
Common Workflows & Use Cases
Verify newly issued TLS certificates before deployment to production ingress controllers, load balancers, or CDN endpoints.
Ensure multi-domain and wildcard SSL certificates include all required production and staging hostnames.
Diagnose certificate chain issues, basic constraints, and key usage extensions in corporate intranet environments.
Quickly inspect expiration dates and signature algorithms to replace legacy SHA-1 certificates with modern SHA-256/ECC certs.
Frequently Asked Questions
Does this tool upload my certificate or public key to any server?
No. ASN.1 decoding and fingerprint calculations happen strictly inside your browser via Web Crypto and pure client-side JavaScript.
Can this tool read private keys?
This tool is designed specifically for public X.509 certificates (.crt, .pem, .cer) and Certificate Signing Requests (CSRs). It does not require or accept private keys.
Does it support both RSA and Elliptic Curve (ECDSA) certificates?
Yes. It parses RSA certificates (2048, 4096-bit, etc.) and modern ECDSA certificates with NIST curves (P-256, P-384, P-521).
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