SSL CSR/Certificate Decoder
Decode a PEM CSR or certificate into its ASN.1 structure.
PEM input
Paste a CSR or certificate (-----BEGIN ...-----)
ASN.1 structure
Best-effort DER structure walk, no external libraries
About the SSL CSR/Certificate Decoder
Paste a PEM-encoded certificate signing request or certificate to see a best-effort walk of its underlying ASN.1/DER structure, including object identifiers, strings, and nested sequences — no external libraries involved.
Examples
Decode a CSR
-----BEGIN CERTIFICATE REQUEST-----...Output
SEQUENCE (612 bytes)
SEQUENCE (...)
OBJECT IDENTIFIER = 2.5.4.3Related tools
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Frequently asked questions
Version 1.0.0 · Updated 2026-08-06 · Runs entirely in your browser