ASN.1 Tree
Hex Dump
Offset
Hex
ASCII
This tool decodes binary ASN.1 data (DER or BER encoding) and displays it as a parsed tree of tags, lengths and values, alongside a hex/ASCII dump of the same bytes. Input can be pasted as Base64 or hex text, or loaded from a file (.der, .ber, .cer, .crt, .p12, .pfx, .p7b, .p7c).
It is intended for inspecting the internal structure of X.509 certificates, PKCS containers and other ASN.1-encoded data during protocol or firmware development, without uploading the data to an external service.