The authenticator that keeps your 2FA secrets on one phone
Most authenticator apps sync your two-factor secrets to every device you own. Each of those devices is another place they can be stolen from. U2 Secured keeps them on exactly one phone, with a zero-knowledge backup for when that phone is lost.
Free on iOS 15.1+ and Android 7.0+. Premium backup $14.99 a year, bought in the app.
Built for people who would rather be safe than synced
One phone, one copy
Your codes and linked apps live on exactly one phone. There is no second tablet, laptop or browser extension quietly holding a copy for an attacker to find.
Zero-knowledge backup
Premium backup is encrypted on your phone with a key derived by Argon2id and sealed with AES-256-GCM before it leaves. Our servers hold ciphertext we cannot read.
Moving phones wipes the old one
Restore onto a new phone and the old handset is retired and wipes its copy. If you did not do it, the old phone tells you someone has your password.
Biometric on every approval
Tap-to-approve sign-ins need Face ID, Touch ID or a fingerprint, and you pick the number shown on the sign-in screen — a tired tap cannot approve.
No analytics or ad SDKs
The app ships with no analytics, advertising or attribution libraries. It is a security tool, not a data source.
Codes for any 2FA account
Standard TOTP codes (RFC 6238) for any account that shows a QR code — Google, Microsoft, GitHub, your bank — fully offline on the phone.
One phone versus sync-everywhere
Sync is convenient, and every synced device is one more copy of the keys to your accounts. Here is the trade U2 Secured makes instead.
| U2 Secured Authenticator | Sync-everywhere authenticators | |
|---|---|---|
| Where your secrets live | On one phone | On every device you sync to |
| Backup encryption | Zero-knowledge (Argon2id + AES-256-GCM) | Varies — Google Authenticator’s sync was reported as not end-to-end encrypted as of 2026 |
| A new device signing in | Retires and wipes the old phone, and warns it | Adds another device holding the secrets |
| Push tap-to-approve with number matching | Built in, for sites that use U2 Secured | Code-only in most free apps |
Google Authenticator: Google committed to end-to-end encryption for sync in 2023; reports in 2026 say it had not shipped (CyberInsider, Tech Insider). Checked October 2026.
Free, or Premium with backup
Free
$0 forever
- Unlimited TOTP codes on your phone
- Push tap-to-approve with number matching
- Biometric app lock
- Works fully offline
- Codes at sign-in on your own Linux computers
Premium
$14.99 per year
- Everything in Free
- Zero-knowledge encrypted backup & restore
- Move to a new phone — the old one wipes itself
- Up to 1,000 items
- Read-only web access to your vault
Premium is bought in the app; the store may offer a 7-day free trial if you are eligible.
Building a product? Give your users tap-to-approve
The same app approves sign-ins for any site that integrates U2 Secured — SDKs for Go, Node and Python, a WordPress plugin, and two-factor for SSH, sudo and Windows sign-in. Read why number matching matters.
Developer docs