This page contains a JavaScript generic ASN.1 parser that can decode any valid ASN.1 DER or BER structure whether Base64-encoded (raw base64, PEM armoring and begin-base64 are recognized) or Hex-encoded.
This tool can be used online at the address http://lapo.it/asn1js/ or offline, unpacking the ZIP file in a directory and opening index.html in a browser
On the left of the page will be printed a tree representing the hierarchical structure, on the right side an hex dump will be shown.
Hovering on the tree highlights ancestry (the hovered node and all its ancestors get colored) and the position of the hovered node gets highlighted in the hex dump (with header and content in a different colors).
Clicking a node in the tree will hide its sub-nodes (collapsed nodes can be noticed because they will become italic).
ASN.1 JavaScript decoder
Copyright © 2008-2018 Lapo Luchini <lapo@lapo.it>
Permission to use, copy, modify, and/or distribute this software for any
purpose with or without fee is hereby granted, provided that the above
copyright notice and this permission notice appear in all copies.
THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
ASN.1 JavaScript decoder Copyright © 2008-2018 Lapo Luchini; released as opensource under the ISC license.
OBJECT IDENTIFIER values are recognized using data taken from Peter Gutmann's dumpasn1 program.