How to use
- Paste your PEM certificate or CSR request (beginning with -----BEGIN CERTIFICATE-----) or select one of the presets.
- The parser immediately processes the ASN.1 structure and calculates the SHA-256 cryptographic fingerprint.
- Inspect the Common Name, protected SAN hostnames, days remaining until expiry, and copy the full JSON report in one click.
FAQ
What are Subject Alternative Names (SANs)?
Subject Alternative Names (SAN) enable a single SSL/TLS certificate to secure multiple different hostnames, subdomains, and wildcard entries simultaneously.
How does expiration checking work?
The tool reads the NotBefore and NotAfter timestamps from the ASN.1 date headers and calculates the exact remaining active days against current local time.
Are certificate keys uploaded to any remote server?
No. The decoding of ASN.1 bytes and generation of SHA-256 fingerprints are performed exclusively inside your web browser via standard Web Crypto APIs.