Paste a CSR or drop the file. See the subject, public key, signature, SAN and extensions, including post-quantum keys such as ML-DSA and SLH-DSA.
Decoding runs entirely in your browser. The CSR is never uploaded.
CSR Decoder reads PKCS#10 requests (RFC 2986) with the extensions from RFC 5280 and the NIST post-quantum object identifiers.