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CSR Decoder

Paste a CSR and review exactly what you are about to send to the certificate authority.

Your text and files never leave your browser — nothing is sent to a server.

Decoded CSR

The decoded fields will appear here.

    How to use

    1. Paste the CSR or drop a .csr file onto the box. Both PEM and DER are accepted.
    2. Every field is listed: domains (CN and SAN), organization details, key type and size, and the signature algorithm.
    3. The badge at the top right shows whether the signature is valid, which proves the request has not been altered.
    4. Before you submit, double-check the spelling of each domain, the SAN list and the key size (RSA 2048 bits or more).

    FAQ

    What is a CSR?

    A certificate signing request is the file you send to a certificate authority to apply for an SSL certificate. It holds your public key and domain details and is signed with the matching private key. The private key itself is not inside the CSR.

    Can I edit the details in a CSR?

    No. The CSR is signed, so changing even one character breaks the signature. Create a new CSR with your private key instead; the CSR and certificate generator can do that right in your browser.

    What happens if the CSR has no SAN?

    Browsers check only the names in the SAN, not the CN. Most CAs add the CN to the SAN automatically, but if you need several domains it is safest to list them all in the CSR.

    Is it safe to paste my CSR here?

    A CSR only contains information that will be public in the certificate anyway, and this page decodes it locally without sending it to any server.

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