CSR Decoder

Decode certificate signing requests locally. Inspect subject, public key, signature algorithm and extensions without uploading the input.

How to use CSR Decoder

Paste one PEM certificate signing request, or select a PEM/DER CSR file, then choose Decode CSR. No private key is needed.

Understanding the results

Review subject attributes, public key, signature algorithm and requested extensions, including alternative names. Decoding does not verify the CSR signature or establish identity. Other CSR attribute values are omitted.

Is my CSR uploaded?

No. Decoder input is processed in your browser and is not added to recent history or favourites.

How can I check a CSR’s common name and alternative names?

Decode the request and review Subject identity and Subject alternative names. Copy details collects those values as text; Download JSON includes the decoded technical fields. A CSR does not contain certificate expiry dates.