Generate SSH key pairs (RSA, Ed25519, ECDSA) with configurable bit length. Download public and private keys.
This tool creates a fresh SSH key pair - RSA, Ed25519 or ECDSA, with bit length where the algorithm allows it - and returns both halves as downloadable files: the private key in OpenSSH format and the one-line public key ready to append to authorized_keys or an account settings page. Everything runs in the browser, so the key material never leaves the machine it was generated on. The surprise for most users: the private key is the whole key. The public key is only derived from it and can be regenerated, while the private key, once lost, is gone forever.
A concrete input and expected output from the current implementation.
Input
Algorithm: Ed25519; Comment: [email protected]; no passphrase
Expected output
Public key (one line): ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAI<random key material> [email protected] Private key (file): -----BEGIN OPENSSH PRIVATE KEY----- <base64-encoded key material> -----END OPENSSH PRIVATE KEY-----
The 25-character prefix is not random: it is the base64 encoding of the fixed header that names the algorithm ('ssh-ed25519') and declares the 32-byte key length, so every Ed25519 public key starts with the same AAAAC3NzaC1lZDI1NTE5AAAAI. Everything after that prefix, and all of the private-key body, is freshly generated random material, so no two runs of the tool ever produce the same pair.
The private key downloads as an OpenSSH-format file beginning with the line -----BEGIN OPENSSH PRIVATE KEY-----. The public key is a single line - key type, base64 blob, comment - derived deterministically from the private key: the same private key always produces the same public key, and ssh-keygen -y can re-print it from the private file later.
Ed25519 is fixed at 256 bits; the scheme's security is defined by that size, so no bit-length selector applies to it. ECDSA is available on the NIST curves P-256, P-384 and P-521, which appear in SSH as nistp256, nistp384 and nistp521. RSA is the configurable one: typically 2048, 3072 or 4096 bits, where larger keys mean a stronger security margin but slower generation and slower connection handshakes.
Yes. The same public key line can be added to authorized_keys on as many servers as you like, and the private key will authenticate to all of them. That convenience is also the exposure: if the private key leaks, everything it unlocks is compromised, which is why some people generate a separate pair per machine.
Save it under ~/.ssh with a sensible name such as id_ed25519, run chmod 600 on it so only your user account can read it, and connect with ssh -i /path/to/key user@host. The private key is meant for your machine only - never paste it into a form or send it to a server. Only the public key is shared.
The example and behavioral notes were checked against the browser implementation. Standards and primary references below define the relevant format, formula, or platform behavior.
Generate strong, random passwords with customizable length, character sets, and complexity requirements.
Analyze password strength with entropy scoring, crack-time estimates, and improvement suggestions.
Create cryptographically random strings for API keys, tokens, salts, and unique identifiers.
Create QR codes for URLs, text, Wi-Fi credentials, vCards, and more with customizable size and colors.
Scan and decode QR codes from uploaded images or your device camera to extract embedded data.
Compute MD5, SHA-1, SHA-256, and SHA-512 checksums to verify file integrity and detect tampering.