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!
IrfanView - IrfanView ... one of the most popular viewers worldwide.
AppleMacSoft DRM Video Converter - Convert iTunes M4V to MP4 on Mac
FastStone Image Viewer - FastStone Image Viewer is a fast, stable, user-friendly image browser, converter and editor.
HandBrake - HandBrake allows users to easily convert video files into a wide variety of different formats.
JPEGView - JPEGView is a small and fast viewer/editor for JPEG, BMP, PNG, GIF and TIFF images.
FFQueue - FFQueue is a FREE and comprehensive GUI for the FFMpeg command line encoder: Convert audio and video from everything to everything!