Open source · Android · Offline
OPEN LOCK
A privacy-focused Android app locker. Pick the apps that matter and guard them behind a PIN or fingerprint — with focus schedules, uninstall protection, and an intruder log. Everything runs on-device.
What is Open Lock?
Open Lock is a free, open-source Android application that locks other apps behind your PIN or fingerprint. It uses Android's standard Usage Access + overlay approach (never an accessibility service) to detect a locked app coming to the foreground and shows a native lock screen over it.
The main app is built with Flutter; the always-on lock enforcement is native Kotlin for reliability. There are no accounts, no ads, and no analytics.
Key features
App locking
Lock any installed app behind a PIN or fingerprint.
Biometric unlock
Fingerprint/face via Android BiometricPrompt, PIN fallback.
Relock policies
Relock immediately, after 1/5/15/30 min, or on screen off.
Focus schedules
Lock chosen apps during time windows on selected weekdays.
Intruder log
Optional silent front-camera capture after failed attempts.
Uninstall protection
Optional device-admin block; turning it off is auth-gated.
Privacy
- Offline core — no accounts, ads, telemetry or trackers.
- Lock settings and intruder photos stay on your device.
- The only network use is an optional GitHub update check.
Security
- PIN stored only as a salted PBKDF2-HMAC-SHA256 verifier.
- Config encrypted at rest (AES-256-GCM); fail-closed keystore.
- FLAG_SECURE hides sensitive screens from Recents/screenshots.
How it works
- 01
Watch
A foreground service reads the current app via UsageStatsManager.
- 02
Detect
A locked app in the foreground triggers the guard per your policy.
- 03
Lock
A native lock screen is drawn over the app (overlay permission).
- 04
Unlock
Your PIN or fingerprint is verified entirely on-device.
Cross-app locking is Android-only by platform design and is best-effort — timing depends on OS polling and OEM background limits.
Latest release
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Why Open Lock?
Most app lockers ask for sign-ups, show ads, or send the list of apps you hide to a server. Open Lock has no servers. What you lock, your schedules, your PIN verifier and any intruder snapshots stay on your phone.
Open source
Open Lock is released under the MIT license. The full source — Flutter app and native Kotlin enforcement — is on GitHub for anyone to inspect, build, or contribute to.