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.
Ceremony - Ceremony is the fastest-growing wedding photo collecting application that allows you to easily collect all your wedding pics from guests.
FastStone Image Viewer - FastStone Image Viewer is a fast, stable, user-friendly image browser, converter and editor.
Wedbox - Wedbox is known as one of the best wedding photo app that lets you easily collect all your wedding photos and videos from guests.
JPEGView - JPEGView is a small and fast viewer/editor for JPEG, BMP, PNG, GIF and TIFF images.
RegexOne - RegexOne offers learning regular expressions with simple, interactive examples.