ASN.1 / DER Decoder
ASN.1 / DER Decoder
Decode DER/BER binary data (hex or Base64/PEM) into a readable ASN.1 tree with tag types, lengths, values, and OID resolution for common cryptographic identifiers.
ASN.1 / DER Decoder
Decode DER/BER binary data (hex or Base64/PEM) into a readable ASN.1 tree with tag types, lengths, values, and OID resolution for common cryptographic identifiers.
Common uses
- Inspect the raw structure of an X.509 certificate
- Decode a DER-encoded public key
- Resolve OIDs in a certificate extension
Also searched as
- asn1 decoder online
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- der to text
- openssl asn1parse online
- decode base64 der
- asn1 tag length value parser
- asn1 oid decoder
- hex to asn1 tree
- decode public key der structure
- pkcs8 structure viewer
- asn.1 tree viewer
Frequently asked questions
How do I decode DER data?
Paste hex, Base64 or PEM into the ASN.1 / DER Decoder and it renders a tree with tag types, lengths and values.
Can it resolve OIDs?
Yes, it names the common cryptographic object identifiers it knows, such as algorithms and distinguished-name attributes. Unknown OIDs are shown as dotted numbers.
What is the difference between DER and BER?
DER is a strict subset of BER with one canonical encoding. The tool decodes definite-length encodings, which covers DER; BER indefinite-length encoding is not supported.
Can I inspect the raw structure of a certificate or key?
Yes, paste the certificate or key as PEM or hex to see its underlying ASN.1 structure.
Is my data uploaded to a server?
No. This tool runs entirely in your browser — your input is processed locally on your device and is never uploaded or stored on a server.