XnView
XnViewMP
FreeXnViewMP: Comprehensive Image Management Suite
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NConvert
FreeEfficient Batch Image Processing with NConvert
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XnRetro (64-bit)
FreeEnhance Your Photos with XnRetro (64-bit)
Windows
XnView Sketch
FreeTransform Your Photos with XnView Sketch
Android
XnSketch (32-bit)
FreeXnSketch: Transform Photos into Artistic Styles
Windows
NConvert for Linux (64-bit)
FreeNConvert for Linux: Versatile Image Converter
Linux