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!
Smart Pix Manager - Smart Pix Manager is a powerful and reliable solution for the management and viewing of all documents, common images, sound (WMA, MP3), and video files (AVI, MPEG), etc.
IrfanView - IrfanView ... one of the most popular viewers worldwide.
StudioLine Photo Basic 4 - StudioLine Photo Basic 4 is a sophisticated image development tool that allows photo editing and multiple presentation options for personal usage.
FastStone Image Viewer - FastStone Image Viewer is a fast, stable, user-friendly image browser, converter and editor.
Photos on macOS - Photos keeps your images organized and accessible. Rediscover favorite shots with Memories. Access them on your devices with iCloud Photos.
JPEGView - JPEGView is a small and fast viewer/editor for JPEG, BMP, PNG, GIF and TIFF images.