Nomacs là một trình xem hình ảnh nguồn mở miễn phí, hỗ trợ nhiều nền tảng. Bạn có thể sử dụng nó để xem tất cả các định dạng hình ảnh phổ biến bao gồm hình ảnh RAW và PSD.

nomacs features semi-transparent widgets that display additional information such as thumbnails, metadata or histogram. It is able to browse images in zip or MS Office files which can be extracted to a directory. Metadata stored with the image can be displayed and you can add notes to images. A thumbnail preview of the current folder is included as well as a file explorer panel which allows switching between folders. Within a directory you can apply a file filter, so that only images are displayed whose filenames have a certain string or match a regular expression. Activating the cache allows for instantly switching between images.

nomacs includes image manipulation methods for adjusting brightness, contrast, saturation, hue, gamma, exposure. It has a pseudo color function which allows creating false color images. A unique feature of nomacs is the synchronization of multiple instances. With this feature you can easily compare images by zooming and/or panning at the exactly same position or even by overlaying them with different opacity.