A real authenticator app in your browser

Guide · updated August 2026

Most 2FA lives on a phone — which is exactly the problem when you are at your desk, your phone is charging in another room, and a login prompt is waiting. KeyNesta's web app is a full authenticator in the browser: add accounts, scan or upload QR codes, generate TOTP codes, import, back up, sync. Nothing to install, works on any OS.

How a vault in the browser stays private

• Your vault is stored encrypted at rest (AES-256-GCM) in your browser's storage.
• The master key is unwrapped from your passphrase (via scrypt) and held only in memory while unlocked; locking discards it.
• Codes are computed locally — generating them requires no network at all.
• Auto-lock closes the window after inactivity; a locked vault is just ciphertext.

The complete design, including its honest limits, is documented in the security architecture.

When the web app is the right tool

• Desk-bound logins: approve 2FA prompts without touching your phone.
• No smartphone, or a shared family device: a browser is all that is required.
• Lost or dead phone: with sync or a backup file, your codes are reachable from any machine you trust — the difference between a bad hour and a bad week.
• Trying before installing: the web app is the full product, free, no sign-up.

One honest caveat

Browser storage is only as durable as your browser profile — clearing site data clears the local vault. Treat the web vault the way you would treat any single device: keep an encrypted backup or sync enabled, and losing a browser costs you nothing.