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Decode ASN.1 DER structures from PEM, base64 or hex into a readable tree. Runs entirely in your browser.
ASN.1 is the notation used to describe the data structures inside X.509 certificates, private keys, CSRs, OCSP messages and most PKCS containers. DER is the binary encoding of those structures. On their own they are an opaque blob of bytes. This tool parses that blob and shows the nested structure: sequences, sets, object identifiers, integers, strings and times, so you can inspect what a certificate or key actually contains.
Input:
300d06092a864886f70d01010b0500
Output:
SEQUENCE { OBJECT IDENTIFIER 1.2.840.113549.1.1.11, NULL }What can I decode with it?
Any DER-encoded ASN.1: certificates, public and private keys, CSRs, PKCS#7/CMS, OCSP responses and similar. Paste the PEM, base64 or hex.
Does it verify signatures?
No. It decodes structure only. It shows you the fields and OIDs, it does not validate certificate chains or signatures.
Why are some values shown as hex?
Binary fields like signatures, keys and unknown types are shown as a hex preview because they have no readable text form.
Is my data uploaded?
No. Parsing runs entirely in your browser.
Decode ASN.1 DER structures from PEM, base64 or hex into a readable tree. Handy for certificates, keys and PKCS containers. Everything runs in your browser.