X.509 PEM Certificate & Public Key Decoder
Inspect ASN.1 base64 certificates, key bit length, payload sizes, and header structures offline.
Execution runs 100% locally inside the browser sandbox using HTML5 Canvas, Web Cryptography Subtle API, and Web Workers. No data is ever transmitted across the network.
Zero network latency. Operates completely offline with zero dependencies on third-party backend servers or cloud services.
Built according to official RFC specifications, cryptographic test vectors, and enterprise-grade data transformation standards.
How to Use X.509 PEM Certificate & Public Key Decoder
Paste your -----BEGIN CERTIFICATE----- or public key content.
Review detected structure type, estimated key length (2048/4096-bit), and binary payload size.
Copy the cryptographic properties for verification.
Frequently Asked Questions
Is it safe to paste certificates into this tool?
Yes, decoding operates 100% in your browser memory via native JavaScript with zero network egress.
Which PEM headers are recognized?
X.509 Certificates, Public Keys (BEGIN PUBLIC KEY, RSA PUBLIC KEY), and PKCS8 Private Keys.
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