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nomacs vs CactusViewer: catalog facts
nomacs	CactusViewer
Free Free and open source under the GPL 3.0.	Free Free and open source under the BSD 2-Clause licence; donations are welcome.
Windows, macOS, Linux	Windows
Opens RAW camera files and Photoshop PSD documents Synchronises pan and zoom between two windows or two machines	Single executable with no installer needed GPU rendering through a custom Direct3D 11 renderer
Not an editor; adjustments are minimal The interface exposes a lot of panels at once	Windows only No packaged releases on the GitHub repository
Downloadable app	Downloadable app
Open source	Open source
License: GPL-3.0	License: BSD-2-Clause
No account needed	No account needed
Works offline	Works offline
Official website Full listing and sources Checked September 21, 2026	Official website Full listing and sources Checked October 2, 2026

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