Photoscape - high quality photo editing software, that enables you to fix and enhance photos.
Retrobatch - Retrobatch is a unique application for automating actions to tens, hundreds, and even thousands of images at the same time
ACDSee - ACDSee is an image viewer that uses very little system resources, and it has a small, sleek size that won't take up much space on your system.
photos2webgallery - Create lovely web galleries directly from macOS Photos app.
JPEGView - JPEGView is a small and fast viewer/editor for JPEG, BMP, PNG, GIF and TIFF images.
FastPictureViewer - A hardware-accelerated image viewer for the modern Windows platform.