UnderKey for Crypto Holders
Your 12 or 24-word recovery phrase is the only thing standing between you and permanent loss of your funds. If someone gets it, they own your wallet. If you lose it, your crypto is gone forever. UnderKey stores seed phrases encrypted on your phone, offline and away from cloud backups, so they're accessible when you need them but never exposed to the internet.
Why crypto holders need offline storage
Most crypto holders know not to screenshot their seed phrase or email it to themselves, but many still store it somewhere that's secretly online:
- Notes apps that sync to the cloud (Apple Notes with iCloud, Google Keep, Evernote, Notion). Even if the note is "locked," it's stored on someone else's server.
- Password managers that sync to their own servers. If the service is breached or the encryption is broken, your seed phrase could be exposed.
- Cloud storage (Google Drive, Dropbox), even if the file is password-protected.
- Photos in your camera roll, which sync to iCloud Photos or Google Photos by default.
Offline storage means your seed phrase exists only on your device, never on a remote server, and never accessible to anyone who doesn't physically have your phone and your unlock pattern.
How UnderKey helps crypto holders
Encrypted secure notes
Store your 12 or 24-word seed phrase as a secure note, encrypted with AES-256 on your device. The note never touches your clipboard for longer than necessary, and it's never uploaded to the cloud.
No cloud sync
UnderKey has no servers and makes no network requests beyond initial purchase verification. Your seed phrase never leaves your phone.
Decoy vaults
If you're travelling with a seed phrase or worried about coercion, you can set up a decoy vault with a different unlock pattern. Put a few harmless documents in it, and if someone forces you to unlock the app, you draw the decoy pattern instead of the real one.
Multiple wallets, one vault
If you hold crypto across multiple wallets (hardware wallet, hot wallet, exchange recovery phrase), you can store all of them in UnderKey. Label each note clearly so you know which phrase belongs to which wallet.
Seed phrases + metal backups: why you need both
UnderKey is for convenient access when you need to recover a wallet or verify a phrase quickly. But it's not a replacement for a durable physical backup:
- If your phone is lost, stolen, or destroyed, your seed phrase is gone. UnderKey doesn't sync to the cloud, so there's no online copy to recover from.
- If you forget your unlock pattern, your vault is permanently locked. There's no password reset or recovery mechanism.
The best setup is:
- One metal backup (a steel plate designed for seed phrases) stored in a safe, safety deposit box, or other secure physical location. Metal backups survive fire, water, and corrosion.
- One encrypted digital copy in UnderKey for when you need to access the phrase quickly without retrieving the metal backup.
The metal backup is your primary, durable copy. The digital copy is your convenient, always-accessible fallback. For a full comparison of storage methods, see our guide on where to store a seed phrase safely.
What not to do
- Don't screenshot your seed phrase. Screenshots sync to iCloud or Google Photos.
- Don't email it to yourself. Email is searchable, unencrypted, and often left logged in on multiple devices.
- Don't keep it in a cloud-synced note. Even if the note is locked, it's still on a server.
- Don't split it across multiple insecure locations. Storing half in email and half in your camera roll doesn't make it twice as secure — it makes it twice as easy to lose.
- Don't rely solely on a digital copy. Always have a metal backup stored separately.
For maximum security
- Create a metal backup as your primary storage. Keep it in a safe or safety deposit box.
- Store a digital copy in UnderKey for quick access when you need to verify the phrase or recover a wallet.
- Clear your clipboard after pasting a seed phrase into UnderKey so other apps can't read it.
- Use a decoy vault if you're travelling with the phrase or worried about border inspections.
- Never upload your seed phrase to cloud storage, email, or any online service.