XnView MP stands for Multi Platform = it is available for Windows, Linux and MacOS. It is a continuation of the older XnView Classic. In my opinion it is a great alternative to Windows photos app or any Linux image viewer that comes preinstalled. I even think it is an alternative to IrfanView. It is really fast and simple to use, supports more than 500 image formats, has built in folder browser, image converter, editor... AND MORE!
Open Camera - Open Camera is an open-source camera app for Android phones and tablets.
IrfanView - IrfanView ... one of the most popular viewers worldwide.
Camera FV-5 - Camera FV-5 is a professional camera application for mobile devices, that puts DSLR-like manual...
FastStone Image Viewer - FastStone Image Viewer is a fast, stable, user-friendly image browser, converter and editor.
AiryCam - Look good in every photo
JPEGView - JPEGView is a small and fast viewer/editor for JPEG, BMP, PNG, GIF and TIFF images.