I built this after noticing my own habit: handing my unlocked phone to someone to show them one photo, then hovering awkwardly while they held it. App lockers already exist. Two things bothered me about them. First, a padlock icon on your home screen tells everyone you have something to hide, so this one can disguise itself as a calculator that actually calculates. Type your PIN, press equals, and the vault opens. Anyone else just does sums. Second, most of them are vague about what they collect, so: your PIN, your locked app list and your settings never leave the device, the PIN is stored with PBKDF2 rather than plain text, and biometrics are handled entirely by Android's BiometricPrompt so the app never sees them. Honest about what it is not: this is a phone privacy tool, not disk encryption. If someone has your unlocked phone and your PIN, it will not save you.

Secure Folder and App Locker

Lock any app behind a calculator nobody thinks twice about

Lock any app behind a calculator nobody thinks twice about