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You can build your Android app with the Android Platform APIs and the following libraries.

Developing with Kotlin? Check out the Kotlin reference for the Android Platform and AndroidX library.

Note: Many Kotlin reference topics are derived from Java-based source code. This means that some Kotlin reference topics might contain Java code snippets.

Android Support Library

Provides a variety of Android feature and utility APIs that are compatible with a wide range of platform versions.


Refactored versions of the Android APIs that are not bundled with the operating system.

AndroidX Test

Includes APIs for testing your Android app, including Espresso, JUnit Runner, JUnit4 rules, and UI Automator.

AndroidX Constraint Layout

Includes ConstraintLayout and related APIs for building constraint-based layouts.

Architecture Components

Includes APIs for a variety of core app components, such as APIs that manage your UI component lifecycle, data persistence, view model, and more.

Jetpack Compose

Jetpack Compose is a modern toolkit for building native Android UI. Jetpack Compose simplifies and accelerates UI development on Android with less code, powerful tools, and intuitive Kotlin APIs.

Android Automotive Library

Provides APIs for building Android Automotive apps.

Databinding Library

Includes APIs to help you write declarative layouts and minimize the glue code necessary to bind your application logic and layouts.

Material Components

Material Components for Android (MDC-Android) help developers execute Material Design to build beautiful and functional Android apps.

Constraint Layout Library

Legacy Support Library ConstraintLayout and related APIs for building constraint-based layouts.

Android Test Support Library

Includes APIs for testing your Android app, including Espresso, JUnit Runner, JUnit4 rules, and UI Automator.

Android Wearable Library

Provides APIs to build apps for wearable devices running Wear OS by Google.

Android Things Library

Provides APIs to build connected devices running the Android Things platform.

Play In-app Billing Library

Provides APIs to help you implement Google Play’s in-app billing and subscription features.

Play Core Library

Provides APIs to help you request, monitor, and manage on demand downloads for Google Play Instant and Dynamic Delivery.

Play Install Referrer library

Provides APIs to securely retrieve referral content from Google Play.

The applock is perhaps the most rudimentary of security apps. The way it works is that it will lock up your other apps from prying eyes. That way you don’t have to worry about someone accessing your Facebook, gallery app, or banking app. They work best when paired with a lock screen lock to give you two layers of security. Which ones are worth getting? We’ll help you out with the best applocks and privacy lock apps for Android! You can learn more about applocks by clicking here! It’s important to note that this is not an end-all-be-all solution for security. It’s good for kids or snoopy friends. However, these provide very little real security for things like stolen phones. We highly recommend continuing to use a lock screen because they are much more secure.

Read Next: How to protect your privacy when using Android 

Applock by DoMobile Lab

Price: Free

Applock by DoMobile Lab is definitely one of the best applocks out there. The app can do the basics like locking up specific apps. It can also lock up specific images and videos. It also includes uninstall protection, fingerprint support, and you can even lock stuff like incoming calls, uninstalling apps, and your various system functions like Bluetooth. The app is free to download and use. You can unlock the premium features either by enabling ads or paying for the premium version via a donation. It’s a strong app and one of our favorites.

AppLock by IvyMobile

Price: Free

AppLock is another one of the better applocks on Android. Like you’ll see, it can lock pretty much any app on your phone. It also boasts the ability to lock photos and videos. The app features an invisible pattern lock as well as a random keyboard just in case someone is trying to peep over your shoulder. You’ll also get theming, the ability to replace the icon so you can hide the app, lock frequency, and more. It’ll even take a picture of people who don’t put the password in right. It’s completely free to download and use. That’s another good perk for this one.

Applock – Fingerprint Pro

Price: $3.99

Applock Fingerprint Pro is a simple, but effective app lock. You choose what apps to lock. The app forces a fingerprint scan in order to unlock them. It works with your device’s fingerprint scanner and it seems to work well overall. It also works with pattern and text passwords as well. Some other features include an image vault, some extra security settings, and more. It has a few annoying bugs here and there. However, we assume the developer will fix those in future updates if they haven’t by the time you read this. We recommend giving it a good try before the refund time is up because this app costs $4.99 with no free version. However, on the plus side, it also has no ads and no further in-app purchases. This same developer does have a free applock, but it’s not the same app.

AppLocker by BGNmobi

Price: Free / $2.99

AppLocker by BGNmobi is a decent overall app lock app. It does most of the same stuff as other applock apps. That includes locking up apps and giving you various ways to access them. You get fingerprint support as well as pattern unlock and a password unlock. It also comes with some customization options and it can prevent other users from uninstalling apps. It won’t dazzle you with a ton of extra or unnecessary features. It’s just a simple app lock that does its job fairly well and it’s also cheap.

App Lock: Fingerprint Password

Price: Free / $0.99

App Lock: Fingerprint Password is a simple and clean looking applock. It can lock up almost any app and you can use a PIN, pattern, or fingerprint to unlock them. The app also supports more than ten languages, has a variety of settings, and it can even be set to proactively protect new apps that you download. Aside from that, it’s one of the more simple applocks on Android. You can download the app for free, but you’ll have to pick up the pro version to get all of the features.

Norton App Lock

Price: Free

Norton is a big name when it comes to antivirus apps. As it turns out, they also provide a free app lock app. It uses a four digit PIN, password, or pattern as its lock system. It also supports photos alongside apps. The app also comes with a recommendations list that lets you know which apps should be locked. That’s a great tool for those who want a more hands-off approach. Like most, it also takes a photo of anyone trying to get into your phone. It can be bypassed if the peeker is clever, but it’s still one of the more solid applocks.

Perfect AppLock

Price: Free

Perfect AppLock is another one of the better applocks out there. It features the basics, including support for locking up WiFi, Bluetooth, and other toggles. It’s also rather frustrating to get passed. It throws fake errors and all kinds of other messages out there. That makes people think there’s a different issue other than an applock. The free and paid versions provide the exact same features. The only difference is that the paid version doesn’t have advertising. It’s a solid all around option, even if it’s name kind of oversells its capabilities a little bit

Smart AppLock

Price: Free

Smart AppLock is another decent free applock option. It’ll lock up your apps and photos, including your settings, toggles, and phone app (for phone logs) to keep all of those safe. It disguises itself as a lock screen. That way people think they’re back there all over again. Along with that, it provides auto-start upon reboot, break-in alerts, delayed app locking, and it has fingerprint scanner capabilities for Samsung devices. It’s a free option that is supported by advertising. The only downside is that it’s pretty easy to uninstall once someone figures out that it’s there.

Smart Launcher 5

Price: Free / Up to $6.99

Smart Launcher 5 is a newer launcher with some decent security features. The app features launcher stuff like ambient theming, adaptive icons, app sorting, gestures, hotkeys, and more. One of its more niche features is an applock. The launcher hides apps you don’t want other people seeing. Additionally, if they do find them, the apps are then protected with a PIN. We would’ve liked to have seen fingerprint reader support, but it’s a whole launcher with an applock built-in and that’s a bit of a rarity in this space. Thankfully, this rarity is also pretty decent as a launcher and as an app lock.

SpSoft AppLock

Price: Free / $4.99

SpSoft AppLock is a decent option for applocks. It features password, pattern, and fingerprint unlocking. That’s good news for those with fingerprint scanners. Like many, it’ll take a selfie of people who try to get into your apps and fail. It also has a bunch of fun little extras. You can make your pattern unlock show up on a grid of up to 18×18 instead of the traditional 3×3. It’ll also show a fake error message instead of a lock if you want it to. The app will even keep your screen on when using certain apps if you want. It’s a good option that also supports over 30 languages.

If we missed any of the best applocks for Android, tell us about them in the comments! To see our complete list of best app lists, click here.


Lock a single app or all of them on Android to keep out curious eyes

There are a few effective ways to lock specific apps on Android devices including guest accounts, screen pinning, third-party apps, and Samsung's Secure Folder. Learn how to lock apps on Android in the foreground or limit access to them altogether.

Instructions in this article apply to all smartphones and tablets running Android 7.0 (Nougat) and later. Upgrade your version of Android to follow along with this guide.

You can lock apps on an iPhone, too.

How to Lock Apps on Android With Screen Pinning

Screen pinning locks an app in open view. Attempting to close it or access the home screen prompts your lock screen security input.

To see which version of Android your device is running, navigate to the Settings and tap About Phone > Software Information.

For Android 9.0 Pie

To enable screen pinning on Android Pie:

  1. Open Settings and tap Security & location.

  2. Tap Advanced.

  3. Tap Screen pinning.

  4. Tap the toggle to enable screen pinning.

    To get the most out of screen pinning and guest accounts, set a secure lock screen pin, password, or pattern beforehand.

  5. Tap Ask for PIN before unpinning to enable it for increased security.

  6. Tap the Overview icon (the square in the black bar at the bottom of your screen), then tap the app you wish to pin.

  7. Tap Pin.

  8. Tap Got it.

  9. Tap and hold Back and Overview simultaneously to unpin the app.

  10. Enter your pin, pattern, password, or biometric security option to unpin the screen.

  11. The app is unpinned.

For Android 8.0 Oreo and 7.0 Nougat

If using the previous versions of Android:

  1. Open Settings, then tap Lock Screen and Security.

  2. Tap Other security settings.

  3. Tap Pin windows.

  4. Tap the toggle to enable screen pinning.

  5. Tap the Ask for PIN before unpinning toggle to enable it.

  6. Tap Overview and open the app window wish to lock to the front.

  7. Tap the thumbtack in the lower-right corner, then tap OK.

  8. Tap and hold the Back and Overview icons to unpin the window.

  9. Enter your pattern, pin, password, or scan your biometric security option to unpin the app.

How to Lock Apps With a Guest Account on Android

To keep all of your apps, settings, and files out of view, enable a guest account before sharing your device with someone. A guest account functions the same as a regular account, but it uses separate instances of the applications on your device.

With a guest account enabled, none of your personal apps or information are accessible.

For Android Pie 9.0 and Oreo 8.0

To create a guest account in Android Pie and Oreo:

  1. Tap Settings, then tap System.

  2. Tap Advanced.

  3. Tap Multiple users.

  4. Tap Guest to switch the user account, or tap the gear icon to the far right to enable phone calls.

  5. Tap the toggle beside Turn on phone calls to enable it if you wish to continue receiving calls while the guest account is active.

  6. Tap OK when the dialog box appears.

  7. Tap Guest to switch the user account.

For Android Nougat 7.0

To enable a guest account on Android 7:

  1. Go to Settings > Cloud and accounts > Users, then tap Guest.

  2. Tap Guest.

Lock Apps on Android With Samsung's Secure Folder

With Secure Folder, you can protect selected apps by locking them with the security option of your choosing. If your device didn't come with Secure Folder and you're running Android 7 or higher, you can download it from Google Play or Galaxy apps.

Secure Folder comes pre-installed on Samsung's flagship devices, including the Galaxy S7/S7 Edge, Galaxy S8/S8+, Galaxy Note 8, Galaxy S9/S9+, etc.

  1. Tap Settings, then tap Biometrics and security.

  2. Tap Secure Folder.

  3. Tap Lock type.

  4. Tap Select lock type, (or a biometric option if available).

  5. Select Pattern, Pin, or Password, then continue by entering your selection and confirming it.

  6. Tap Secure Folder from your app drawer, then tap Add apps.

  7. Select the apps you wish to include in Secure Folder, then tap Add.

  8. Tap Lock in the upper-left corner.

  9. A brief message appears indicating Secure Folder is now locked. Attempting to access Secure Folder prompts the lock type you selected earlier.

  10. Enter your pattern, pin, password, or scan your biometric security option.

  11. The app is unpinned.

How to Lock Apps on Android With Mobile Applications

Mobile tools such as App Lock and Security Master lock your apps and protect your files. Most apps that lock or protect your device's content require a few permissions and system privileges, such as displaying over other apps and accessibility usages.

How to Set a Password for Apps With Norton App Lock on Android

Norton App Lock by Symantec is a useful tool for protecting applications and private files stored on your device. Norton App Lock is free to download and supports Android 4.1 and up. You can restrict access to all apps or choose specific apps to lock:

  1. Go to Norton App Lock's Google Play page, then tap Install.

  2. Once installed, tap Open.

  3. Review the License Agreement, Terms of Use, and the Privacy Policy, then tap Agree & Launch.

  4. Tap OK.

  5. Tap the Allow display over other apps toggle.

  6. Tap Setup.

  7. Tap Norton App Lock Service.

  8. Tap the Use service toggle.

  9. Tap OK.

  10. Draw an unlock pattern or tap Switch to Passcode, then enter a password.

  11. Draw your unlock pattern again to confirm, or tap RESET to re-enter it.

  12. Tap Choose Google Account.

  13. Tap the Google account you wish to use for password resetting, then tap OK.

  14. Tap Continue.

  15. Tap the yellow lock whenever you want to enable or disable app lock.

  16. Once apps are locked, only the passcode you created earlier will grant access.


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