About the SSH Key Validator
When SSH authentication fails, the question is usually "is this key even valid, and is it the key I think it is?" This validator parses OpenSSH private keys locally in your browser, checks passphrase correctness, and reports the key type, bit length, fingerprint, and comment — without the key ever leaving your machine.
It understands modern OpenSSH-format keys (BEGIN OPENSSH PRIVATE KEY) as well as legacy PEM formats, which is exactly the distinction that breaks older tooling and CI systems expecting PEM-formatted RSA keys.
Frequently asked questions
Why does my CI system reject a key that works locally?
Probably format. ssh-keygen has generated OPENSSH-format keys by default since OpenSSH 7.8, but some libraries (older Paramiko, some Java SSH clients) only parse legacy PEM. Convert with ssh-keygen -p -m PEM -f keyfile — and note this rewrites the file in place, so work on a copy.
Which SSH key type should I generate today?
Ed25519 (ssh-keygen -t ed25519). Keys are small, fast, and immune to the nonce-reuse failures that plague ECDSA. Use RSA 4096 only when a legacy system cannot accept Ed25519. ECDSA and DSA are not worth choosing for new keys.
Is it safe to paste a private key into a browser tool?
This tool parses keys entirely client-side with no network transmission, which you can verify in the browser's network tab. Still, treat any pasted production key as a judgment call: for highly privileged keys, validating on a trusted machine with ssh-keygen -y -f keyfile is the conservative option.
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