Ralpha Image Resizer - High-speed image batch conversion tool
Shrink O'Matic - Shrink O'Matic is an AIR application to easily (batch) resize (shrink) images.
ImBatch - ImBatch is a batch image processor with a nice graphical user interface.
Caesium Image Compressor - Compress your pictures up to 90% without visible quality loss.
ImageOptim - Faster web pages and apps.
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.