ImBatch - ImBatch is a batch image processor with a nice graphical user interface.
DVDVideoSoft Image Convert and Resize - Free Image Convert and Resize is a compact yet powerful program for batch mode image processing.
Caesium Image Compressor - Compress your pictures up to 90% without visible quality loss.
XnConvert - XnConvert is an easy image converter for graphic files, photos and images available on Windows...
ezgif.com - Ezgif.com is simple online gif maker and toolset for basic animated gif editing.
PhotoBulk - PhotoBulk is a bulk image editor for Mac that was created for the best experience of batch editing. With this image editing software for macOS you can add watermarks, optimize and resize pictures, convert images or rename photos in bulk.