Frequently Asked Questions
Everything you need to know about UnderKey: how it works, what it encrypts, and what happens to your documents.
Do I need an account?
No. There is no sign-up, no email and no login. You open the app, draw a pattern and your vault exists — only on your phone.
Can UnderKey see my documents?
No. Everything is encrypted with AES-256 on your device and never sent to a server. We don't run one that could receive your files.
How do decoy vaults work?
Each pattern opens its own vault. Draw a second pattern, put a few harmless documents in it, and that's the vault you open if someone insists.
What if I lose my phone?
UnderKey keeps nothing in the cloud, so there is no online copy for anyone to find — including you. Keep printed copies of truly critical documents somewhere safe.
Is it really free?
Yes, for up to 10 items total. All encryption, decoy vaults, and reminders are included. Pro removes the limit.
What happens if I forget my unlock pattern?
Your vault is permanently locked. There's no password reset, no recovery email, and no way for us to unlock it for you. The encryption key is derived from your pattern, and we don't store it.
Does it work offline?
Yes. All encryption, unlocking, and document access happens on your device. You can open your vault even with no internet connection.
Can I use it on multiple devices?
No. Your vault exists only on the device where you created it. UnderKey has no cloud sync, so documents don't transfer between devices.
What's the difference between the free and Pro versions?
Free lets you store up to 10 items (documents, photos, notes) total. Pro removes the limit. All encryption, decoy vaults, OCR, and reminders are included in both.
How do I upgrade to Pro?
Tap "Upgrade" in the app and choose weekly ($1.99/week), yearly ($19.99/year), or lifetime ($39.99 once). Payment is handled by the App Store or Google Play Store.
What platforms does UnderKey support?
iOS and Android. The app is native to each platform and optimized for performance and security.
Does UnderKey collect any data?
No. We collect no analytics, no telemetry, and no usage data. We don't track how many vaults you have, how many documents you've stored, or how often you unlock the app.
What third parties are involved?
Google ML Kit (on-device OCR for expiry date detection), RevenueCat (subscription management with an anonymous ID), and Apple/Google (payments and platform services). None of them see your documents. Full details: /security/
Can I export my documents?
Yes. You can export individual documents from the app to share them or move them elsewhere. The exported copy is decrypted, so handle it carefully.
What file types can I store?
Photos, scans, PDFs, and secure text notes. The document scanner produces images (JPEG/PNG). You can also import PDFs and other image files from your photo library or Files app.
Does UnderKey block screenshots?
On Android, yes — screenshots and screen recordings are blocked while the app is unlocked. On iOS, Apple doesn't allow third-party apps to block screenshots, but UnderKey blurs the app preview in the app switcher.
Can I backup my vault?
UnderKey doesn't provide cloud backup by design. To back up your vault, keep printed copies of critical documents in a safe at home, or store a second encrypted copy on an external drive (not in the cloud).
What happens if I uninstall the app?
Your vault and all its documents are deleted when you uninstall the app. Make sure you have backups of critical documents before uninstalling.