ASN.1 JavaScript decoder

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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 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).

WARNING: starting from 2023-02-26 this website is using some ES6 features, which can break it for older browsers (though it is still working on IE11).
You can access last version before ES6 on githack.


ASN.1 JavaScript decoder Copyright © 2008-2023 Lapo Luchini; released as opensource under the ISC license.

OBJECT IDENTIFIER values are recognized using data taken from Peter Gutmann's dumpasn1 program.