SSL Certificate & Private Key Pair Checker
Pair-check an SSL certificate against a private key or a CSR file
Features
Strict matching by public key hash
Determine whether the public keys of the certificate, private key, and CSR match using SHA-256
Two pair-check modes
Switch between certificate-and-private-key and certificate-and-CSR to verify
Show hash values for comparison
On mismatch, line up both SHA-256 hashes to visualize the difference
Try it instantly with samples
Load valid and invalid samples with one click to test the behavior
How to use
Choose the check type
Select the comparison target from the "SSL certificate and private key" or "SSL certificate and CSR" tabs
Paste the certificate and its counterpart
Paste the SSL certificate and the private key or CSR into their respective fields in PEM format
Run and check the result
Press the run button and check the match/mismatch result and the public key hash values
Use cases
Pre-check before installing a certificate
Prevent mismatched certificate and private key combinations before configuring the server
Avoid mixing up multiple certificates
When managing multiple files during renewal, use it to identify the corresponding key
Confirm consistency from a CSR
Verify whether the issued certificate uses the same key pair as the CSR from the application
Isolate installation errors
Determine in advance whether an installation error is caused by a pair mismatch
Basic Knowledge
What is a Certificate and Private Key Pair?
An SSL certificate contains a public key that is mathematically linked to a corresponding private key. If this pair does not match, the server cannot use the certificate, making pair verification before deployment essential.
Common Scenarios Where Pair Mismatches Occur
Mismatches often happen when an old private key remains after annual certificate renewal, private key files from multiple domains are confused, or an old certificate is used after recreating a CSR. These issues can be prevented by verifying the pair before server configuration.
Safety and privacy
Runs entirely in your browser
Your input data is processed only within your browser and is never sent externally.
Processing only in your browser
certificate and key matching is processed entirely within your browser, and input data is not sent to any server.
Communications encrypted with HTTPS
Page loading is also encrypted by TLS, and content cannot be read by third parties.
No transmission to third parties
Input content is not sent to external services such as ad networks or trackers.
No automatic saving of results
the certificate and private key you enter and input suggestions are not stored on the server.
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