Passwordless Login with Passkeys (WebAuthn)

Passwords are the worst part of almost every app. Users reuse them, forget them, and get phished out of them. And you, the operator, carry the liability of storing them. Passkeys are the industry's answer, and by 2026 they've gone mainstream: every major platform supports them, and big consumer apps default to them. Here's what they are and why adding them is one of the higher-leverage security upgrades you can make.

What a passkey actually is

A passkey replaces the password with a pair of cryptographic keys. When a user signs up, their device generates a key pair: a private key that never leaves the device (guarded by the phone's secure hardware), and a public key that you store on your server. To log in, the device proves it holds the private key by signing a one-time challenge. Typically unlocked with the same Face ID, fingerprint, or PIN the user already uses for their phone.

The crucial part: there is no shared secret. You only ever store a public key, which is useless to a thief. There's nothing to leak in a breach, nothing to reuse across sites, and nothing for a fake login page to capture.

A passkey can't be phished, reused, or stolen from your database. Because the only secret never leaves the user's device.

Why it's phishing-resistant by design

This is the feature security teams care about most. A passkey is cryptographically bound to your domain. If a user lands on a look-alike phishing site, their device simply won't offer the passkey. It knows the domain doesn't match. Phishing, the single most common way accounts get taken over, just stops working. No amount of user gullibility can hand the credential to an attacker.

The thing that made passkeys finally usable

Early device credentials had a fatal flaw: lose the phone, lose the key. Modern passkeys fixed this by syncing through the platform's keychain. ICloud Keychain, Google Password Manager, or a third-party manager. Get a new phone, sign into your platform account, and your passkeys are there. That sync is what turned a clever idea into something you can actually ship to ordinary users without flooding support with lockouts.

How you add them

The underlying standard is WebAuthn (part of FIDO2), supported natively by browsers and mobile OSes. You don't implement the crypto yourself. A well-maintained server library handles generating challenges and verifying signatures, and the browser/OS handles the device side. Two short flows: registration (create a key pair, store the public key against the user) and authentication (issue a challenge, verify the signed response).

// Registration, conceptually
const options = await server.startRegistration(user);   // server: challenge
const credential = await navigator.credentials.create(options); // device: keypair
await server.finishRegistration(credential);             // server: store public key

A smart rollout keeps passwords (or email magic links) as a fallback and offers passkeys as the better option, then nudges users to enroll. You don't have to flip everything overnight. You just stop making the password the only door.

The takeaway

Passkeys are faster for users, immune to phishing, and remove your most dangerous liability. Stored passwords. The tooling is mature, the platforms all support it, and users already know the gesture from unlocking their phones. If you want passwordless login done properly in your app, get in touch, or see what we've shipped.