nomacs

nomacs is a desktop image viewer with browsing, inspection, adjustment, and comparison tools. It is best suited to people who review images or compare processing stages, rather than readers seeking a full image editor.

Overview

Founded in 2011, nomacs is free for private and commercial use under the GNU General Public License v3. Its roots in image-processing workflows show in its synchronized comparison tools, while its adjustment controls are useful for modest corrections, not a replacement for a dedicated editor.

It handles common image formats, including RAW and PSD, but support can depend on Qt image plugins, KImageFormats, and optional build features. If a particular format matters to your work, check that the build you choose supports it.

Key features

Browse and inspect

Semi-transparent widgets can show thumbnails, metadata, and histograms, and users can add notes to images. Folder thumbnail previews and text or regular-expression filename filters help narrow a collection. Browsing images inside ZIP or MS Office files is a useful extra when image files are bundled in documents or archives.

Adjust images

Brightness, contrast, saturation, hue, gamma, and exposure controls cover common tonal and color changes. Pseudo-color rendering can display false-color images. These tools make nomacs more than a passive viewer, but they do not make it a full editing suite.

Compare processing stages

Multiple instances can synchronize panning and zooming, and images can be overlaid at different opacity. That makes it easier to inspect corresponding details across versions, particularly for image-processing work. Readers who only need to browse photos may not benefit as much from these specialized controls.

Pricing

The nomacs plan costs nothing. It includes private and commercial use under GPLv3, with no paid tier or free-trial period to weigh. The no-cost license is a strong fit for individual and commercial users alike; the practical trade-off is that format availability can vary by build, so confirm support for essential files before relying on it.

Platforms

nomacs supports Windows, Linux, macOS, FreeBSD, and OS/2. Downloads include Windows 64-bit installer and portable packages, Linux packages, Flatpak and AppImage, plus macOS arm64 and x86_64 builds. Windows XP and Vista are not supported in development since version 3.0; version 2.4.6 can be used on those systems.

Who it's for

Choose nomacs if you want a free desktop viewer that can inspect metadata and histograms, filter and browse collections, make basic adjustments, and compare image-processing stages. It is less suitable if you need a comprehensive editing workflow or depend on a format without first checking support in your chosen build. The project directs bug reports and feature requests to its tracker and welcomes contributions such as translations, ports, and code.

Pros and cons

• Pros: Free for private and commercial use under GPLv3, with no paid plan to unlock its core viewer.
• Pros: Synchronized zoom and panning plus opacity overlays serve detailed image comparisons.
• Pros: Browsing, metadata, histograms, filename filters, and basic adjustments bring more utility than simple image opening.
• Cons: Format support depends partly on plugins and optional build features, which can complicate workflows built around particular formats.
• Cons: Adjustment controls are practical for basic changes but do not position nomacs as a full editor.

Alternatives

Browse the Photo Viewer Software or File Viewer Software directories to compare more options.

• ImageGlass offers a free GPLv3 Classic plan and a free trial, making it an alternative to consider if those terms better fit your needs.
• XnConvert has a free plan for private, educational, and nonprofit use, while a company license is priced at 6.50 EUR; consider it if those licensing categories align with your use.
• Geeqie is a free GPLv2 option for readers who prefer that license.
• Pineapple Pictures is a free MIT-licensed viewer; a paid itch.io purchase offers experimental additional format support.
• qView is a free, open-source GPLv3 image viewer.
• ApolloOne is a macOS-only alternative with a free version and a 1-Year Standard Subscription for $14.99 a year.
• FastStone Image Viewer is Windows-only, with free personal and educational use and a commercial lifetime license priced at $34.95 a month.
• PhotoQt is a free, open-source viewer for Linux and Windows.

Verdict

nomacs is a strong choice for people who want a no-cost viewer that can inspect, adjust, and compare images, especially across processing stages. Its main reason to choose it is the breadth of those tools under a free commercial-use license; look elsewhere if you need a full editor or guaranteed support for a particular format across builds.