1. Telegram
Telegram is one of the most used available for Android and iOS. Learn from the Telegram code — how an instant messaging app with super security works.
2. NewPipe
is somewhat a lightweight version of YouTube that unlocks a heap of otherwise restricted features. The app comes with a simple UI but is packed with some powerful features — background player, picture-in-picture mode, download support for offline playback, and on top, it’s a completely free open-source Android app with no ads. The main plus point of this app is its “extended privacy” — NewPipe protects user privacy since no proprietary Google APIs is there in the code and only sends information that is required to get video and channel details.
Google Play:
3. Lawnchair Launcher
Lawnchair Launcher is a simple open-source bringing Pixel features. If you are developing a new Android launcher, then refer to the codes of Lawnchair, because it may help you to integrate different Android customization options into your app.
Google Play:
4. Minimal ToDo
Minimal ToDo is a lightweight Android app for the to-do list. This app will help beginners to develop a simple yet powerful to-do list app.
Google Play:
5. Snapdrop
Snapdragon is an incredible application that makes on the same network a much more seamless process. Just install the app on Android and on other devices use any browser of choice, and go to:. Tap on the device name and select files to transfer. That’s it. The Snapdrop code is a perfect choice to learn wireless file transfer in Android.
Google Play:
6. Amaze File Manager
Amaze File Manager is a lite file manager app for Android with material design guidelines. There are a lot of things you can learn from this app, like how to manage files on SD cards, cloud services support, AES Encryption and Decryption of files for security, etc.
Google Play:
7. Open Camera
Open Camera is a fully featured and open-source camera app for Android devices. The project will help you know about how to add the auto-stabilization option on a camera app, how to take photos remotely by making a noise, multi-touch gestures, and single-touch control on the camera app, etc.
Google Play:
8. APKUpdater
APKUpdater is a tool designed to simplify the process of finding updates for your installed apps. It provides similar functionality to an app store, but instead of depending on a single source, it aggregates the results from APKMirror, Aptoide, F-Droid, and Google Play.
Google Play:
9. Watomatic
Watomatic is an auto-reply application for both WhatsApp and Facebook Messenger. Watomatic sends an automated reply to every incoming message. With this, you can set your own auto-reply message and set a reply frequency.
Google Play:
10. OmniNotes
Fully-featured lightweight open-source Android note-taking application. With OmniNotes app source code will help to develop your own note taking application with features like basic add, modify, archive, trash, and delete notes actions, insertion of an image, audio and generic file attachments in notes, including a To-do list feature on your note app, etc.
Google Play:
11. Super Clean Master
Similar to the Clean Master app, Super Clean Master is used to clean up some junk data from your Android device. Super Clean Master project will help you to understand the collection and detection of junk files and how to handle it in an elegant way. the project is a little bit complicated, it will take some time for beginners to fully grasp the source code.
Google Play:
12. AntennaPod
AntennaPod is a podcast manager and player that gives you instant access to millions of free and paid podcasts. This open-source Android app will teach you different integration techniques, managing playback settings, etc.
Google Play:
13. Mutify
Mutify is a Spotify ad silencing app for Android. This open-source Android app auto-detects whenever Spotify plays an ad, and once it does, it will immediately turn your phone’s volume down to zero. If you don’t have Spotify premium subscription, then Mutify is a pretty great solution.
Google Play:
14. TimberX Music Player
TimberX Music Player is one of the new open-source Android apps written in Kotlin. TimberX comes with a simple UI with great features. The app source code will help you learn data binding and dependency injection with KOIN. The app has cross-platform support — it works on phones, Android Wear, Android Auto, Chromecast and other cast devices, and Google Assistant.
Google Play:
15. LeafPic
LeafPic is a fluid, material-designed alternative gallery app for Android. It comes with all stock gallery features and the source code is really a helpful guide for a beginner Android developer.
Google Play:
16. K-9 Mail
K-9 Mail is an open-source email client for Android with support for multiple accounts, search, IMAP push email, multi-folder sync, flagging, filing, signatures, BCC-self, PGP/MIME & more. This project helps you to understand the working of an email client and how to implement IMAP, POP3, and Exchange 2003/2007.
Google Play:
17. Easy Sound Recorder
Easy Sound Recorder is a simple open-source sound recorder app with material design. The project will help you to learn Android voice recording integration and manipulation in apps.
Google Play:
18. FreeOTP Authenticator
FreeOTP is an open-source developed by Red Hat. The app source code teaches you the working of an authenticator app, and how to generate one-time passwords on your mobile devices which can be used in conjunction with your normal password to make your login nearly impossible to hack.
Google Play:
19. Keepass2Android Password Safe
Keepass2Android is open-source. The projects make you understand the security features of a password manager and how to safeguard and autosave passwords using built-in cloud storage options.
Google Play:
20. ML Manager
A modern, easy and customizable open-source app manager for Android. The project helps you to learn how to extract installed & system apps and save them locally as APK, uninstallation process of apps, etc
Google Play: