Here are some of the best open source apps for Android.
Firefox is one of the most popular open source projects out there. The popular browser has mobile apps as well as desktop apps. It covers all the basics, including cross-platform synchronization, privacy browsing modes, extensions and bookmarks. Firefox underwent a big change in 2018 with better and faster browsing.
Firefox Fast & Private Browser
FreeOTP is a two-factor authentication application. It works like Google Authenticator or Microsoft Authenticator. You configure it and it provides security codes for access. It supports TOTP and HOTP protocols and should work with all websites that support those protocols. The application is free, open source and maintained by Red Hat.
Company: Red Hat
Lawnchair Launcher is a launcher for Android. It looks a lot like Pixel Launcher, but with more features. It includes Google Now integration, support for different sized icon packs, a blur mode and other tweaks. It is free, open source and highly functional.
Nextcloud is an open source private cloud storage application. It works pretty well. You install a server on your computer and the app on your phone. Then you use your computer as your cloud storage system. Another option is to pay another company to host your files for you with Nextcloud. You can sync your files, photos and documents. The user interface is pretty clean and has features like multi-account support, automatic uploading of photos and videos, and you can share files. It's not as powerful as Google Drive, but it's much more private.
Open Camera is a camera app that replaces the main camera app to give it more functionality. It includes full manual controls, configurable hotkeys, HDR support, a widget, and support for some external microphones. It's free, though you can make a $1.99 donation.
Company: Mark Harman
OsmAnd and AddressToGPS
OsmAnd is an open source navigation application. It uses OpenStreetMap for its maps, so everything is free. It has turn-by-turn directions along with route reset when you get off track. It also has offline support. AddressToGPS is an app on F-Droid that feeds data from Google Maps and forwards it to OsmAnd. That means you can get OpenStreetMap and Google Maps information from the same place. It requires some patience to set it up.
OsmAnd Maps & GPS Offline
Phonograph is one of the few musical open source applications. It has a nice design and, in addition, the app includes themes, Last.fm integration, tag editing, playlists, widgets and more. Shuttle is another open source application. You can use the premium version for free if you use Google Play Pass.
Phonograph Music Player
Company: Karim Abou Zeid
QKSMS is one of the few open source SMS applications. It comes with all standard features including personalization, MMS, privacy features, Wear OS (Android Wear) support and TalkBack support.
Company: Moez Bhatti
Simple Mobile Tools
Simple Mobile Tools is a Google Play developer with a wide range of open source apps, including a calendar, a gallery, a drawing app, a contacts app, a note-taking app, a file manager, a flashlight, a music player, a camera, a clock and more. Basically, you can replace all the apps on your device with these. Each of them is completely open source and all of them work offline.
Descargar de la Google Play
VLC is one of the most popular players out there and is available on many more platforms than most. It is also open source and supports a number of unusual formats, such as DVD ISOs, live streaming links and many audio codecs.
VLC for Android