You have two near-identical RAW exports and need to see which one is sharper. nomacs, a free image viewer from TU Wien, opens RAW and psd files along with the usual formats, and can show a histogram and metadata in semi-transparent panels over the picture.
A university project under the GPL-3.0
nomacs is developed by TU Wien, and its project site is nomacs.org. The source is open and licensed under the GNU General Public License v3. The developer says it is free for private and commercial use.
Bug reports and feature requests go through the project's tracker, according to the store description. The app is in the photo viewers category, and the listed alternatives are XnView MP, Honeyview, ImageGlass and FastStone Image Viewer.
RAW, PSD, zip archives and synced windows
The viewer opens common image formats, including RAW and PSD. It can also browse images inside zip or MS Office files, which can be extracted to a folder. Metadata stored in an image can be displayed, and you can add notes to images.
Semi-transparent widgets show thumbnails, metadata or a histogram over the picture. A folder thumbnail preview and a file explorer panel are included, and a filename filter accepts a plain string or a regular expression. Turning on the cache makes switching between images instant.
Editing is basic: brightness, contrast, saturation, hue, gamma and exposure. A pseudo color function creates false color images. The feature the developer calls unique is synchronizing multiple instances, so you can zoom and pan to the same position or overlay images at different opacity.
Version 3.22.4 and where it runs
This page covers version 3.22.4 for Windows, a 45.3 MB download released on October 1, 2026. The package ID is nomacs.nomacs and the app is free. Beyond Windows, the developer lists Linux, FreeBSD, Mac and OS/2 as supported platforms.
What's new in 3.22.4
Version 3.22.4 brings security updates to the libraries nomacs uses on Windows. The changelog also links two VirusTotal scan reports.
nomacs pros and cons
Pros
- Free, open source under GPL-3.0, with commercial use allowed
- Opens RAW and PSD files along with common formats
- Synchronized instances allow side-by-side zoom, pan and opacity overlay
- Filename filter accepts regular expressions
- Browses images inside zip and MS Office files
Cons
- Editing covers only basic adjustments such as brightness and gamma
- Few visual previews are available before installing
- Minimum Windows version is unclear
Is nomacs safe?
nomacs is developed by TU Wien and released as open source under GPL-3.0, so its code can be inspected. The changelog for version 3.22.4 mentions security updates in the libraries it uses and links two VirusTotal scans, which you can open and check yourself.
How to install nomacs
- Press the download button to get the official file.
- Run the installer you saved and confirm the Windows security prompt if the publisher matches.
- Follow the setup steps, then start nomacs from the Start menu.
