ASN.1 Decoder
Parse, decode, and inspect ASN.1 structures (BER, DER, CER, PER, APER, XER, JER) from Base64, Hex strings, or binary files.
Quick Tutorial & Instructions
1. Choose Input Source
Select Base64 or Hex String to paste encoded data directly, or choose File to upload a binary certificate/key file (e.g.,
.der, .cer, .p7b).
2. Select Encoding Rule
Choose DER for standard X.509 certs & keys, BER/CER for telecom/LDAP data, PER/APER for cellular/3GPP streams, or XER/JER for XML/JSON representations.
3. Decode & Inspect
Click Decode to view the structured Tag-Length-Value (TLV) Tree along with byte offsets, tag classes, decoded primitive values, and plain text dump.