Our verdict: nomacs is a capable open-source viewer that goes further than most free viewers in comparing images. Synced windows zoom and pan together, which makes it easy to spot differences between two shots. Its interface is more technical than simple viewers like ImageGlass.
About nomacs
nomacs is an open-source image viewer licensed under the GPLv3 and free for private and commercial use. It opens all common formats, including camera RAW and Photoshop PSD files, and can browse images inside ZIP archives and Microsoft Office files.
Semi-transparent panels show thumbnails, metadata and a histogram over the image. A file explorer panel and a filename filter with regular expressions help in large folders. Basic adjustments cover brightness, contrast, saturation, hue, gamma and exposure, plus crop, resize and rotate.
What it does well
- Synced viewers. Several nomacs windows zoom and pan together, or overlay images with adjustable opacity.
- RAW and PSD viewing. Opens camera RAW and Photoshop files alongside common formats.
- Info panels. Thumbnails, metadata and a histogram shown over the image.
- Image adjustments. Brightness, contrast, saturation, hue, gamma, exposure, crop, resize and rotate.
- Archive browsing. Views images inside ZIP and Microsoft Office files without unpacking them.
Who it is for
Good fit
Photographers and technical users who compare images or need metadata at a glance.
Look elsewhere
People who want a minimal viewer with as few panels and options as possible.
Pros and cons
Pros
- Free and open source, including commercial use
- Unique synced comparison mode
- RAW and PSD support
- Portable version available
Cons
- Busy interface with many panels and options
- Editing is limited to basic adjustments
How to install nomacs
Download the 64-bit MSI installer, or the portable ZIP from the same page if you prefer not to install. Turn on the cache in the settings for instant switching between images. To compare two pictures, open them in two nomacs windows and enable synchronization.
Questions about nomacs
Is nomacs free?
Yes. It is open source under the GPLv3 and free for private and commercial use.
How do I compare two images in nomacs?
Open each image in its own nomacs window and turn on synchronization. Zooming and panning in one window then moves the other to the same position.
Is there a portable version of nomacs?
Yes. The official installation page links a portable ZIP for Windows next to the MSI installer.
