nomacs is described as 'Free, open source image viewer, which supports multiple platforms. You can use it for viewing all common image formats including RAW and psd images' and is a very popular Image Viewer in the photos & graphics category. There are more than 50 alternatives to nomacs for a variety of platforms, including Windows, Linux, Mac, Flathub and Xfce apps. The best nomacs alternative is IrfanView. It's not free, so if you're looking for a free alternative, you could try IrfanView or XnView MP. Other great apps like nomacs are XnView Classic, FastStone Image Viewer, qView and Gwenview.
nomacs alternatives are mainly Image Viewers, but if you're looking for
Image Editors or Photo Managers you can filter on that. Other popular filters include
Open Source. These are just examples - use the filter bar below to find more specific alternatives to nomacs.