nomacs is a small, fast open source image viewer which is able to handle the most common image formats including RAW images. Additionally it is possible to synchronize multiple viewers.
A synchronization of viewers running on the same computer or via LAN is possible. It allows to compare images and spot the differences (e.g. schemes of architects to show the progress).
The software is written in C++ and uses Qt which allows for a platform independent user interface.
Image viewing features include:
- Supports the most common image formats including RAW.
- Fast thumbnail preview.
- Metadata HUD panel.
- Zoomable grid preview of thumbnails.
- Display exif information.
- Frameless view.
- Change transparency of windows.
- Display overview/histogram/file info.
- File filtering/searching/sorting.
- Improved anti-aliasing.
- Hide menubar and toolbar.
- Slideshow:
- Image information (e.g. date created).
- Play/pause with user defined time interval.
- Adjustable background color.
- Plugins to extend functionality.
- Cross-platform support – runs under Linux, macOS, OpenBSD, FreeBSD, and Windows.
Website: github.com/nomacs/nomacs
Support:
Developer: Markus Diem, Stefan Fiel, Florian Kleber
License: GNU General Public License v3.0

nomacs is written in C++. Learn C++ with our recommended free books and free tutorials.
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Great image viewer.