X.509 Certificate Decoder

Parse and dissect public key infrastructure (PKI) X.509 certificates to examine extensions, subject metadata, algorithm signatures, and key specs.

Paste X.509 Certificate PEM Data (-----BEGIN CERTIFICATE-----):

X.509 Quick Summary:

Ready to decode X.509 certificate...

Full ASN.1 Attribute Breakdown: Ready

X.509 Specification Reference

X.509 certificates are formatted using Abstract Syntax Notation One (ASN.1) rules serialized typically via Distinguished Encoding Rules (DER).

X.509 v3 introduced extensible fields allowing customized data inclusions like Basic Constraints, Key Usage policies, and SAN definitions.

No. All X.509 decoding routines run locally client-side inside your browser engine without network transit.

Object Identifiers (OIDs) like `2.5.4.3` map directly to standard attributes such as Common Name (CN) within distinguished names.

Yes, self-signed certificates follow the exact same X.509 v3 syntax framework and parse correctly using standard PEM boundaries.