List of Open Source Software Android apps

There are many free and open source android apps are available which doesn't require unwanted permissions or collect any data or show any ads. Many apps could not be found on Google Play.

• F-Droid

F-Droid is an installable catalogue of FOSS (Free and Open Source Software) applications for the Android platform. The client makes it easy to browse, install, and keep track of updates on your device.

• MoneyWallet

MoneyWallet is an advanced expense manager that allows you to track your expenses and plan budgets. You can organize your data using custom categories, events, places and people tags. The user interface is in material design, clear, simple and extremely customizable. It fits on all devices. It's simply your best expense manager.
F-droid :
https://f-droid.org/en/packages/com.oriondev.moneywallet/

• Simple Gallery - Photo and Video Manager & Editor

Simple Gallery is a highly customizable lightweight gallery app loved by millions of people for its great user experience. Organize and edit your photos, recover deleted files with the recycle bin, protect and hide files and easily view a huge variety of different photo and video formats including RAW, SVG, GIF, panoramic and much more.
F-droid :
https://f-droid.org/en/packages/com.simplemobiletools.gallery.pro/