Which SSH key type should I use?

Ed25519 is the modern default — small, fast and very secure. Use RSA (3072/4096-bit) for older servers that don't support Ed25519, and ECDSA when a specific NIST curve is required.

Are the keys real, working OpenSSH keys?

Yes. The public key is a standard authorized_keys line and the private key is in native OpenSSH (openssh-key-v1) format, ready to drop into ~/.ssh. The tool also shows the SHA256 fingerprint and randomart, exactly like ssh-keygen.

Can I use these keys with PuTTY on Windows?

Yes. Every generated key also exports a PuTTY .ppk file alongside the OpenSSH format, so you can load it directly in PuTTY/Pageant without running PuTTYgen.

How do I add a passphrase to the private key?

The generated private key is unencrypted. After saving it, run 'ssh-keygen -p -f id_ed25519' to add a passphrase locally.

SSH Key Generator — Ed25519, ECDSA & RSA (ssh-keygen online)

Generate Ed25519, ECDSA or RSA SSH key pairs in OpenSSH format with SHA256 fingerprint and randomart, plus a PuTTY .ppk export — a private, in-browser ssh-keygen. Public key, private key and authorized_keys line.