Certificate and Private Key Matcher
Check whether a pasted certificate matches a pasted RSA private key.
Runs in your browser. Nothing is uploaded — your input is processed on this device and discarded when you close the tab.
Certificate and Private Key Matcher
How to use this tool
- Enter your values in the fields above.
- Press Generate to see the result.
- Use Load sample to try the worked example, Copy result to copy it, or Clear to start again.
Worked example
A matching RSA certificate and private key pair reports a match, because the modulus parsed from the certificate equals the modulus parsed from the private key.
What this tool does not do / Limits
Only RSA keys are compared, by parsing the modulus from both pasted blocks. EC and other key types are reported as unverified, never as a match, and this tool does not validate the certificate chain or expiry.
Frequently asked questions
Is pasting a private key safe here?
The check runs entirely in your browser and nothing is uploaded, but as a precaution use a test key, never a production private key, in any web page.
What does a match actually prove?
Only that the certificate public key and the private key share the same RSA modulus. It does not prove the certificate is trusted or unexpired.
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