Key Pair Generator

Generate RSA, ECDSA, and Ed25519 public/private key pairs securely in your browser — PEM, DER, or OpenSSH (GitHub / ssh) — 100% private, keys never leave your device

About Key Pair Generator

Overview

This is a secure key pair generator that creates RSA, ECDSA, and (in supported browsers) Ed25519 keys right in your browser. No information is ever sent to a server, so everything stays on your device. You can export PEM or DER for X.509-style use, or OpenSSH format: a one-line public key for GitHub and ssh, plus a PKCS#8 PEM private key that OpenSSH accepts with ssh -i.

Features

  • 🔒 100% private. All keys are made in your browser.
  • 🛡️ No data is sent to a server.
  • Supports RSA (2048, 3072, 4096 bits), ECDSA (P-256, P-384, P-521), and Ed25519 where supported.
  • Uses the secure Web Crypto API.
  • PEM and DER formats for OpenSSL-style workflows.
  • OpenSSH public line (ssh-rsa, ecdsa-sha2-*, ssh-ed25519) for GitHub and authorized_keys.
  • One-click copy to clipboard.
  • Download keys for backup.
  • Real-time key generation.
  • Shows detailed key information.
  • Standard key formats that work with OpenSSL and OpenSSH.
  • Good for SSL/TLS, signatures, and SSH authentication.

How to Use

  1. Pick the key type: RSA, ECDSA, or Ed25519 (when your browser supports it).
  2. Choose the key size for RSA or the curve for ECDSA.
  3. Select the output format: PEM, DER (Base64), or OpenSSH for GitHub / ssh.
  4. Click "Generate" to make new keys.
  5. Copy or download the keys.
  6. Keep the private key safe and never share it.

FAQ

What is a key pair?

A key pair is two linked keys: a public key and a private key. The public key can be shared for encryption or signature verification. The private key must stay secret for decryption or signing. They are mathematically linked but you cannot derive the private key from the public key.

What is the difference between RSA and ECDSA?

RSA uses the difficulty of factoring large numbers for security. ECDSA uses elliptic curve mathematics. ECDSA provides the same security level as RSA but with much smaller keys, making it faster and more efficient for the same security strength.

Is it safe to generate keys in my browser?

Yes, this tool uses the Web Cryptography API, which provides secure cryptography in the browser. All key generation happens on your device and keys never leave your browser. Your private keys stay completely private and are never transmitted over the network.

How do I use OpenSSH format with GitHub?

Select OpenSSH (GitHub / ssh) as the output format, generate keys, then paste the entire public key line into GitHub under Settings → SSH and GPG keys. Save the private key to a file (for example id_ed25519), set permissions with chmod 600, and use ssh -i with that file to authenticate.