App Lock by Bestools crossed 134 million Android installs by promising one-tap fingerprint protection for WhatsApp, Instagram, the gallery, and any other app on the phone. The catch is what users keep flagging in reviews and on r/Android: heavy ads in the free tier, accessibility-service permission requirements that double as a giant data hose, intruder-selfie features that quietly pre-process every camera frame, and a “vault” that hides photos by renaming the folder rather than encrypting them. We compared seven App Lock alternatives that handle the same per-app PIN, fingerprint, and pattern protection with cleaner permissions, real encryption on hidden files, or the system-level isolation that built-in Android tools already offer.
Quick comparison
| App | Best for | Free tier | Open-source | Vault encryption |
|---|---|---|---|---|
| AppLock by DoMobile | Most-installed alternative | Yes (with ads) | No | Folder rename |
| Norton App Lock | Brand-trust no-ads free | Yes (no ads) | No | None |
| Smart AppLock | Polished free locker | Yes | No | Local PIN-protected folder |
| Samsung Secure Folder | Samsung built-in | Built-in | No | Samsung Knox (real encryption) |
| Shelter | Open-source work profile | Yes (free, F-Droid) | Yes | Real Android Work Profile isolation |
| Island | Open-source advanced isolation | Yes (free, F-Droid) | Yes | Real Android Work Profile isolation |
| Keepsafe Photo Vault | Encrypted photo vault only | Yes (limited) | No | AES-256 encryption |
Why people leave App Lock
- Heavy ads in the free tier. Banner ads on the lock screen, interstitials between settings, and full-screen ads on lock setup are documented across Trustpilot and the Play Store.
- Accessibility-service permissions. App Lock requires Accessibility Service to detect which app is launching. That permission is one of the most powerful on Android and is frequently abused by other apps in the same category.
- Vault is a folder rename. Hidden photos are not encrypted; they are moved into a folder the gallery does not show by default. A file manager or another gallery app can still see them.
- Pro-gated essentials. Disguise icon, intruder selfies, and app-uninstall protection sit behind the paid tier. The free experience nags constantly to upgrade.
- Permissions sprawl. All Files Access, Camera, and Notifications are all requested at install. Some are needed for the feature set; not all are needed by default.
The alternatives
AppLock by DoMobile, the most-installed alternative
DoMobile Lab’s AppLock has been around since 2012 and remains the most-installed app locker on Android by lifetime downloads. The feature set is similar to Bestools’ App Lock (PIN, pattern, fingerprint, photo vault, intruder selfie) with a longer track record and a more conservative ad load on the free tier.
The vault still hides files by folder rename rather than encrypting them, the disguise-icon feature requires the paid Pro tier, and AppLock’s privacy policy is comparable to other freemium lockers in the category.
DoMobile vs Bestools’ App Lock: longer history, more conservative ads, broadly similar feature set. The trade is reputation and stability for not solving the underlying vault-encryption gap.
Norton App Lock, best brand-trust no-ads free
Norton App Lock comes from the antivirus brand and is the cleanest free option in the category: no ads, no upsells, no Pro tier nag. Pattern, PIN, and fingerprint locking on any installed app, optional intruder selfie, and a “Sneak Peek” mode that shows whoever picked up the phone what they tried to open.
There is no photo vault, no app-disguise, and Norton has not pushed major feature updates in some time. The Norton brand carries weight for users who want to install something whose parent company they recognise.
Norton vs Bestools’ App Lock: cleaner permissions, no ads, no upsells, but a thinner feature set. Best fit for users who only want per-app locking and trust the brand.
Smart AppLock, best polished free locker
Smart AppLock by ThinkYeah is the polish leader on the freemium side. The lock screen designs are clean, multiple themes ship in the free tier, fingerprint and pattern unlock are baked in, and the photo and video vault includes a separate PIN.
The free tier shows ads inside settings and prompts for accessibility access, and the vault stores files in a hidden folder rather than encrypting them. The Pro upgrade unlocks intruder selfie, fake cover screen, and ad removal at a one-time price.
Smart AppLock vs Bestools’ App Lock: better-looking UI, comparable feature depth, similar permission asks. The cleanest free experience in the conventional locker category.
Samsung Secure Folder, best built-in option
Samsung Secure Folder is the right answer for anyone on a Galaxy phone. It uses the Samsung Knox secure-environment to create a separate workspace where apps, files, and accounts live encrypted at rest. PIN, pattern, password, fingerprint, and iris (where supported) all work as the unlock method, and the icon can be hidden from the home screen entirely.
Secure Folder is Samsung-only. There is no equivalent for non-Samsung Android devices, and apps inside Secure Folder can only access the data inside it (which is exactly the point but takes some setup).
Secure Folder vs Bestools’ App Lock: real Knox-backed encryption, no ads, no third-party permissions, but only available on Samsung hardware. The best option for Galaxy users by a wide margin.
Shelter, best open-source work-profile isolation
Shelter uses the standard Android Work Profile to clone selected apps into an isolated workspace that the system itself protects. The host app is open-source, ships through F-Droid (and Google Play), and the isolation is enforced by Android, not by an accessibility service. There are no ads, no upsells, and no vendor.
Shelter does not lock individual apps with a PIN screen; it freezes them or hides them inside the work profile. That is a different mental model from a lock screen and takes a few minutes to set up. Some apps detect the work-profile clone and refuse to run.
Shelter vs Bestools’ App Lock: real Android-level isolation instead of an accessibility-service overlay, fully open-source, ad-free. Different model from a per-app PIN; better fit for users who want privacy isolation rather than just a screen lock.
Island, best advanced open-source isolation
Island goes further than Shelter on configuration. It uses the same Work Profile isolation but adds Greenify-style hibernation, per-app permission control, and the ability to keep one Instagram account in the work profile while another runs in the main profile. Open-source, F-Droid build available, and clearly maintained.
Island has a steeper learning curve than Shelter or any conventional locker. The setup uses ADB on first run for some advanced features, and the documentation expects a user who has worked with Android internals before.
Island vs Bestools’ App Lock: more powerful and more flexible than any locker, fully open-source, but a real time investment for setup. Best fit for power users who already know what they want to isolate.
Keepsafe Photo Vault, best encrypted photo vault
Keepsafe is the photo vault that actually encrypts. Photos and videos imported into Keepsafe are stored AES-256 encrypted in a private app folder, and the cloud backup tier (Premium) keeps the encrypted blobs in Keepsafe’s storage. PIN, fingerprint, and a fake-PIN decoy mode all ship in the free tier.
The free tier limits total storage to 100 photos for cloud backup, the Premium tier (around $4.99 per month) lifts that, and Keepsafe is photo-and-video-focused rather than a general app locker.
Keepsafe vs Bestools’ App Lock’s vault: real encryption rather than folder rename, dedicated photo workflow, and the option to back up encrypted blobs to Keepsafe cloud. Loses on per-app locking, which is not the use case it solves.
How to choose
If you have a Samsung phone, Samsung Secure Folder is the clear answer: real Knox encryption, no third-party permissions, no ads. If you want an open-source approach that uses Android’s own isolation features rather than an accessibility-service overlay, pick Shelter for simplicity or Island for power. If you want a conventional locker without the ads, Norton App Lock is the cleanest free pick. For polish at the same price, Smart AppLock. For an encrypted photo vault that actually deserves the name, Keepsafe Photo Vault.
Stay on Bestools’ App Lock if the free-tier ads do not bother you and the feature set covers what you need. Just understand that the photo vault is not real encryption, and avoid hiding anything sensitive there.
Frequently asked questions
Is App Lock safe to use on Android? The app itself is not known to ship malware, but it requires Accessibility Service to detect which app is launching, which is one of the most powerful permissions on Android. The vault hides photos by folder rename rather than encrypting them, so anyone with a file manager can still see them.
Which App Lock alternative is fully free with no ads? Norton App Lock is the cleanest free pick: no ads, no upsells, no Pro tier nag. Shelter and Island are also fully free and open-source through F-Droid.
Does Samsung Secure Folder encrypt my files? Yes. Secure Folder uses the Samsung Knox secure environment, which encrypts files at rest with hardware-backed keys. It is the only option in this list with real encryption built in by default.
Can I lock apps without an Accessibility Service permission? Samsung Secure Folder, Shelter, and Island all work without the Accessibility Service because they use Android’s built-in Work Profile or Knox isolation. Conventional lockers (Bestools’ App Lock, AppLock by DoMobile, Smart AppLock, Norton App Lock) need the Accessibility Service to detect which app is launching.
What is the difference between a lock and a vault? A lock prompts for a PIN or fingerprint when an app is opened; the underlying app data is unchanged. A vault moves or encrypts files into a separate location protected by a password. Bestools’ App Lock has both, but the “vault” is actually a hidden folder, not an encrypted store.
Are there open-source App Lock alternatives? Yes. Shelter and Island are both open-source, ship through F-Droid, and use Android’s own Work Profile isolation rather than an accessibility-service overlay. Both are maintained and actively used.
