Public key fingerprint calculator
Calculate the standard fingerprints of a public key, certificate or OpenSSH key in your browser. Compare SPKI pins, OpenSSH SHA256 values, JWK thumbprints and certificate fingerprints in one report.
Input is exactly one key, certificate or certificate request of up to 200000 characters, with DER data up to 65536 bytes. Text with more than one PEM block, such as a full chain, is refused. Parsing and hashing run locally in your browser with Web Crypto. Download the JSON report with every fingerprint format. Paste PEM text, an ssh-ed25519 or ssh-rsa line, or a public JWK. Up to 200,000 characters. Review the settings before running.
Your result
How to use Public key fingerprint calculator
- Paste a PEM public key, certificate or certificate request, an OpenSSH public key line or a public JWK.
- Run the tool.
- Compare the fingerprint in the format your other tool shows, then download the report.
Useful next steps
Fingerprint formats
SPKI SHA-256 in Base64 is the pin-sha256 value from RFC 7469 (April 2015). OpenSSH SHA256 is unpadded Base64 of the SHA-256 of the key blob, as printed by ssh-keygen -l. The JWK thumbprint follows RFC 7638 (September 2015). Certificate fingerprints hash the whole DER certificate, matching openssl x509 -fingerprint.
Supported keys
RSA, EC P-256, P-384 and P-521, and Ed25519 keys are supported. Other keys still get SPKI fingerprints where the structure is valid. Key sizes match ssh-keygen -l and OpenSSL, so an Ed25519 key shows 256 bits. Legacy OpenSSH MD5 fingerprints are not offered.
What it does not do
A fingerprint identifies a key; it does not prove who owns it. Certificates are decoded, not validated against any trust store, and nothing is fetched from the network.