SSH Key Generator

SSH key pairs are the standard way to authenticate to a remote server without typing a password every time. A key pair consists of two mathematically linked files: a public key, which you upload to a server's authorized_keys list or paste into a hosting provider's dashboard (GitHub, GitLab, a cloud VPS, etc.), and a private key, which stays on your machine and is used to prove your identity whenever you connect. Because the two are linked by the mathematics of RSA, the server can verify you hold the private key without that key ever leaving your device or being sent over the network. This tool generates that pair the same way a browser would generate any other cryptographic key — through the Web Crypto API's crypto.subtle.generateKey() call, which is implemented natively by the browser, not by any JavaScript on this page. That means the actual key generation, including the random number generation that makes the key unguessable, uses the browser's own cryptographically secure random source rather than anything written for this widget. What this widget does add is the formatting: browsers export keys in generic formats (SPKI for public keys, PKCS#8 for private keys) rather than the OpenSSH-specific formats that tools like ssh-keygen, ssh-copy-id and most servers expect, so this tool parses the exported public key bytes and re-encodes them into the OpenSSH wire format by hand, and wraps the exported private key bytes into a standard PEM block. The public key format used by OpenSSH is a compact binary encoding: the string "ssh-rsa", the public exponent, and the modulus, each prefixed with its length and concatenated, then the whole thing is base64-encoded and given a human-readable prefix and an optional trailing comment (typically an identifier like a username and hostname, purely for your own reference — the comment carries no cryptographic weight and can be anything, or left blank). This tool lets you set that comment before generating. A couple of scope notes worth being upfront about. First, this generates RSA-2048 keys only — no Ed25519 option is offered, because as of now Ed25519 support inside the Web Crypto API is not consistently available across browsers, and building a hand-rolled Ed25519 implementation in JavaScript to work around that would be a much larger undertaking with a correspondingly larger risk of a subtle bug undermining the whole point of the tool. RSA-2048 remains a widely accepted, well-supported key size and algorithm for SSH authentication, so this is a reasonable default even if it is not the newest option available. Second, while everything genuinely runs client-side and nothing is transmitted, a browser tab is still not the same trust boundary as a purpose-built, security-audited command-line tool. For any key you will actually use to access production infrastructure, ssh-keygen (bundled with OpenSSH) remains the standard choice, is available on effectively every Linux, macOS and modern Windows install, and has been scrutinised far more thoroughly over a much longer period. Treat this generator as a fast, convenient way to produce a working key pair for testing, learning, or a throwaway scenario — not as a wholesale replacement for your existing key management workflow.