New · Zero-knowledge authenticator

Your 2FA codes,
end-to-end encrypted.

You set the password. Your device encrypts every 2FA secret with AES-256-GCM before it ever leaves. Our servers only see ciphertext — and neither can anyone else.

Download on the App Store

GET IT ON Google Play

All platforms

6 platforms

Synced

4 devices · just now

Encrypted locally

AES-256-GCM

Server · blind

0x8f3a··b1c4

ZERO OTP — Vault

ZEROOTP

Search 14 accounts…

+ Add

3 synced

Vault

All (14)

Dev (6)

Finance (5)

Social (3)

Devices

iPhone 15

MacBook Pro

iPad Air

GitHub

483 217

Google

129 483

AWS

751 826

₿

Coinbase

293 847

𝕏

Twitter

394 821

Discord

582 193

GET THE APP

Download for any device.

Free on all 6 platforms. One account, one master password — sync everywhere.

Free forever · End-to-end encrypted · No tracking

Platforms

iOS · Android · macOS · Windows · Linux · Web

AES-256

Encryption

GCM with authenticated tags, on-device

Server knowledge

Only ciphertext crosses the network

100%

Offline capable

TOTP codes generated locally, RFC 6238

PLATFORMS

One vault.
Every device.

Same codes. Same encryption. Zero setup friction — anywhere you are.

Pocket

iOS · ANDROID

Face ID · Offline

Native iOS & Android. Biometric unlock, haptic copy feedback, and a lock-screen widget that never shows codes in plaintext.

ZEROOTP

All Dev

GitHub 2FA

418 902

Google 2FA

203 114

AWS

AWS root 2FA

891 337

₿

Coinbase 2FA

672 059

iOS 15+ · Android 10+ · iPadOS 15+

Desktop

MACOS · WINDOWS · LINUX

⌘K·menubar

Keyboard-first client. Global hotkey, menu-bar access, grid view that scales to 200+ accounts. One keystroke to copy any code.

All · 42

Work

Personal

Crypto

Infra

GitHub

418 902

AWS root

891 337

Stripe

920 451

Vercel

337 088

macOS 13+ · Windows 10+ · Linux (AppImage/deb)

Coverage at a glance How ZERO OTP compares across platforms

vs. others

Platform	ZERO OTP	Google Auth	Authy	2FAS
iOS & Android	✓	✓	✓	✓
macOS	✓	✗	✓	✗
Windows	✓	✗	✓	✗
Linux	✓	✗	✗	✗
Web Browser	✓	✗	✗	✗
Zero-Knowledge Sync	✓	✗	✗	✗

FEATURES

Security is not
a compromise.

Built around a single idea: your secrets should be unreadable to anyone but you — including us.

01 · CORE

Zero-knowledge encryption

Your device encrypts every 2FA secret before it hits the wire. Our database stores only ciphertext — we literally can't read it.

DEVICE Plaintext OTP

AES-256-GCM

PBKDF2-derived key

DATABASE Unreadable

Decrypt

on-device

OTHER DEVICE Plaintext OTP

Password never transmitted · same key, same vault, every device

02 · KEY

Master password, derived locally

You type a password. Your device runs PBKDF2-HMAC-SHA256 with 600,000 iterations to derive the vault key. We never see any of it.

input

••••••••••••

PBKDF2-HMAC-SHA256 · 600k

key

0x8f3a··b1c4··e7f2

Stays on your device. Always.

Works offline, always

Codes generated locally via RFC 6238. Never waits on a server.

ONLINE

OFFLINE · SAME

End-to-end encrypted sync

Vault flows between your devices as ciphertext. Only you can unlock it.

4 DEVICES SYNCED

Easy import

QR scan, otpauth:// paste, or import from a ZERO OTP backup file.

ZERO-KNOWLEDGE

HOW IT WORKS

The server never
sees anything useful.

You set the master password. Your device derives a key from it locally with PBKDF2-HMAC-SHA256 (600k iterations), then encrypts every 2FA secret with AES-256-GCM before any network call. The server only ever stores ciphertext — without your password, decryption is mathematically impossible.

Password never transmitted

Your master password stays on your device. Only encrypted ciphertext crosses the network.

Ciphertext-only database

AES-256-GCM with authenticated tags — tamper-evident. A full server breach reveals nothing useful.

No recovery by design

Forget your master password? Nobody — not even us — can recover your vault. That's the guarantee.

Your device

password → PBKDF2 → key

LOCAL

483 217

Plaintext OTP · never leaves

AES-256-GCM encrypt

Server database

stores ciphertext only

BLIND

0x8f3a··b1c4··e7f2··a021··9bdf··cc4e

Without your password, this is noise.

Decrypt on-device

Another device

same password → same key

LOCAL

483 217

Same vault · unlocked, on-device

HOW IT WORKS

Three steps.
Sixty seconds.

Set a master password once. Scan. Done. Your vault is live on every device.

SCAN

Scan any QR code

Works with every TOTP service. Accepts any standard otpauth:// QR code or URI.

ENCRYPT

Encrypted on your device

AES-256-GCM with a key derived from your master password via PBKDF2-HMAC-SHA256 (600k iterations). Happens before any network call.

SYNC

Instant on every device

Your encrypted vault syncs to all 6 platforms. Same master password unlocks it everywhere.

FAQ

Common questions.

Is ZERO OTP free?

Yes. Unlimited accounts, offline TOTP, on-device encryption and cross-device sync are all free. If premium features land later, the core security model stays free forever.

Which platforms are supported?

ZERO OTP runs on iOS, Android, macOS, Windows, Linux and the Web. The same encryption model and the same master password work across every one — you set up once and every device sees the same vault.

How do I sign in? Is there a password to log in?

No login password. You enter your email, we mail you a short one-time code, and verifying it returns a device token that's bound to your device. There's nothing for an attacker to phish or reuse — no static credential ever leaves your device.

What's the difference between sign-in and the master password?

Two different things on purpose. Sign-in (magic-link email code) proves you own the email and lets your device talk to the API. Master password never leaves your device — it derives the encryption key used to protect your OTP secrets. The server never sees it and can't help you recover it.

What does "zero-knowledge" actually mean here?

When you set a master password, your device derives a 256-bit key with PBKDF2-HMAC-SHA256 (600,000 iterations, per-user salt) and encrypts every TOTP secret with AES-256-GCM before it hits the network. Only the resulting ciphertext is stored on our servers. Your password, your derived key and your plaintext secrets never leave the device.

What happens if I forget my master password?

We can't recover it — that's the whole point of zero-knowledge. We never see it, so there's nothing on our side to reset. Your encrypted vault becomes unreadable. Pick a password you'll remember (a passphrase of 4–6 uncommon words works well) and keep a copy somewhere only you can reach.

What happens if I lose my phone?

Install ZERO OTP on a new device, sign in with a fresh magic-link code, and your encrypted vault downloads automatically. Enter your master password and everything decrypts locally. You can also revoke the lost device from Settings so its token immediately stops working.

Can I export my vault and leave?

Yes, any time — it's your data. ZERO OTP exports a plain-text JSON file containing your otpauth:// URIs so you can read it, copy individual entries, or import it into any other authenticator app. Everything happens on your device. No lock-in, no gatekeeping.

Does it work without an internet connection?

Yes. TOTP codes are generated locally per RFC 6238 — the app never asks the server for a code. A network is only needed to sync new secrets between your own devices.

How does sync between my devices actually work?

Every device polls a lightweight version endpoint (just an integer) a few times per minute. When something changes, it pulls the updated vault and decrypts it locally. With a master password set, only ciphertext ever moves across the wire.

Can I bring my accounts into ZERO OTP?

Yes. Scan any standard otpauth:// QR code to add accounts one by one, or restore from a ZERO OTP encrypted backup file to bring everything across at once.

Do you ever store the 6-digit codes?

Never. The rotating code is computed on your device from the encrypted secret + the current time. It's displayed, copied to your clipboard if you tap it, and forgotten — it never reaches our servers or any log.

Your 2FA codes, end-to-end encrypted.