nomacs is described as 'small, fast image viewer able to handle the most common image formats including RAW images. Additionally it is possible to synchronize multiple viewers' and is a well-known app in the Photos & Graphics category. There are more than 25 alternatives to nomacs for a variety of platforms, including Windows, Linux, Mac, Xfce and PortableApps.com. The best alternative is IrfanView. It's not free, so if you're looking for a free alternative, you could try ImageGlass or JPEGView. Other great apps like nomacs are FastStone Image Viewer (Free Personal), XnView (Free Personal), Preview (Free) and qView (Free, Open Source).
- XnView is a utility for viewing and converting graphic files. XnView is provided as FREEWARE for private non-commercial or educational use (including non-profit organization). View 117 alternatives to XnView
- Free Personal • Proprietary
XnView vs nomacsXNview-MP (not listed) might be a good alternative. And it's multi-platform... I do use it, it has a lot of features, but is *not* small or simple.