ASN.1 Inspector
Dissect the ASN.1 structure of DER/PEM data into a readable tree. Paste your data, then click to dissect it. Everything runs on your device, nothing is sent to a server.
Everything runs in your browser. Your data is never sent to our servers.
Example
Example Input
-----BEGIN PUBLIC KEY-----…
Example Output
Sequence → Integer → …
How to Use
- 1Paste your data (PEM/Base64/token) into the Input field.
- 2Click the button (or press Ctrl+Enter) to dissect it.
- 3Read the decoded result in the Output field.
About ASN.1 Inspector
ASN.1 (Abstract Syntax Notation One) is the notation underlying almost all cryptographic formats: certificates, keys, CSRs, and more. DER is its binary encoding.
This tool parses DER/PEM and shows its ASN.1 tree (SEQUENCE, INTEGER, OID, etc.) so you can see exactly how the structure is laid out.
It is very useful for deep debugging and learning crypto formats. For a high-level view of a certificate, use the X.509 Certificate Viewer.
FAQ
Are my data or keys sent to a server?
No. ASN.1 Inspector runs entirely in your browser using the Web Crypto API and client-side libraries. Your data, passwords, and keys never leave your device.