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Certificate key matcher

Compares a pasted certificate, CSR or public key against a pasted private key entirely in the browser and reports match or no match, with passphrase handling for encrypted keys.
Certificate, CSR or public key in PEM formPrivate key in PEM form

Paste key material on both sides to run the comparison.

The comparison reduces both pastes to their public key and compares that, not the metadata around it, which is why a certificate and a bare key file still line up. What it does not do: it derives no public key for Ed25519 or X25519 private keys (their PEMs carry only the seed), skips EC keys saved without an embedded public point, and decrypts only PBES2 encrypted keys (PBKDF2 with AES-CBC), the scheme modern OpenSSL writes. Nothing is uploaded: the parsing, the decryption, and the comparison all happen in this tab.
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More web & auth tools

- Certificate & CSR (/web/certificate)
- SSH key inspector (/web/ssh-key)
All web & auth tools (/web)

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Canonical HTML: https://nutter.tools/web/certificate-private-key-matcher
Markdown version: https://nutter.tools/web/certificate-private-key-matcher.md
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