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nomacs
What it is
nomacs is a free, open-source image viewer for Windows, Linux, and macOS. It opens common image formats, including RAW and PSD, and offers tools to browse, inspect, adjust, and compare images. Semi-transparent widgets can show thumbnails, metadata, and histograms, and users can add notes. The viewer can access images inside ZIP or MS Office files, preview folder thumbnails, and filter filenames with text or regular expressions. Adjustments include brightness, contrast, saturation, hue, gamma, and exposure; it can also create pseudo-color images. For comparisons, separate nomacs instances can synchronize panning and zooming, while images can be overlaid at different opacity. Format availability depends in part on Qt image plugins, KImageFormats, and optional build features such as ENABLE_RAW and ENABLE_TIFF, so it may vary by build. Downloads include Windows installer and portable packages, Linux packages and Flatpak/AppImage, and macOS arm64 and x86_64 builds. The introduction also lists FreeBSD and OS/2 as supported systems. nomacs uses GNU General Public License v3 and is free for private and commercial use.
For and against
For
- Opens common formats, including RAW and PSD.
- Can display metadata, histograms, and thumbnails.
- Supports synchronized viewing and opacity overlays for comparisons.
- Free for private and commercial use.
Against
- Available formats can vary by plugins and build features.
- Windows XP and Vista are not supported for future development since version 3.0.
- Windows XP and Vista use requires version 2.4.6.
The verdict
nomacs covers image viewing, browsing, basic adjustments, and comparison across its listed desktop platforms. Check the build’s format support if a particular image type is essential.
Who it suits
nomacs suits people who want a desktop viewer for image browsing, basic adjustments, metadata, or image comparison. It may also be useful to image-processing users comparing images at different stages.
Plans and prices
nomacs
Free for private and commercial use · GNU General Public License v3
Read 2 Oct 2026 · nomacs.org
On the record
- Downloads
- The installation page lists Windows 64-bit installer and portable packages, Linux packages and Flatpak/AppImage, and macOS arm64 and x86_64 builds.nomacs.org · read 2 Oct 2026
- Editing
- Image adjustments include brightness, contrast, saturation, hue, gamma, and exposure, as well as pseudo-color false-color images.nomacs.org · read 2 Oct 2026
- File browsing
- nomacs can browse images in ZIP or MS Office files, show a folder thumbnail preview, and filter filenames by text or regular expression.nomacs.org · read 2 Oct 2026
- Formats
- The documented format support depends partly on Qt image plugins, KImageFormats, and optional build features such as ENABLE_RAW and ENABLE_TIFF.nomacs.org · read 2 Oct 2026
- Image comparison
- Multiple nomacs instances can synchronize panning and zooming, and images can be overlaid at different opacity for comparison.nomacs.org · read 2 Oct 2026
- Image information
- Semi-transparent widgets can display thumbnails, metadata, and histograms; users can add notes to images.nomacs.org · read 2 Oct 2026
- Integrations
- The FAQ describes its original purpose as helping image-processing users compare images at different processing stages.nomacs.org · read 2 Oct 2026
- License and use
- nomacs is licensed under GNU General Public License v3 and is free for private and commercial use.nomacs.org · read 2 Oct 2026
- Other supported systems
- The introduction also lists FreeBSD and OS/2 as supported platforms.nomacs.org · read 2 Oct 2026
- Product
- nomacs is a free, open-source image viewer for viewing common image formats, including RAW and PSD images.nomacs.org · read 2 Oct 2026
- Support
- The documentation directs users to the project tracker to report bugs or request features, and invites contributions such as translations, ports, and code.nomacs.org · read 2 Oct 2026
- Windows compatibility
- The FAQ says Windows XP and Vista are not supported in future development since nomacs 3.0, though version 2.4.6 can be used on those systems.nomacs.org · read 2 Oct 2026
