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!
Meitu - Meitu is a standalone photo editing application that offers almost all those features and photo editing tools that lets the smartphone users personalize their photos like a professional makeup artists and fashion designers.
IrfanView - IrfanView ... one of the most popular viewers worldwide.
Facetune - Facetune is a fun and powerful portrait & selfie photo editor!
FastStone Image Viewer - FastStone Image Viewer is a fast, stable, user-friendly image browser, converter and editor.
SUPERIMPOSE X - Superimpose X is the most powerful and intuitive photo-editing application.
JPEGView - JPEGView is a small and fast viewer/editor for JPEG, BMP, PNG, GIF and TIFF images.