ImageOptim - Faster web pages and apps.
ImBatch - ImBatch is a batch image processor with a nice graphical user interface.
XnConvert - XnConvert is an easy image converter for graphic files, photos and images available on Windows...
DVDVideoSoft Image Convert and Resize - Free Image Convert and Resize is a compact yet powerful program for batch mode image processing.
JPEGmini - JPEGmini - The Photo Optimization Tool Trusted by Tens of Thousands Image Perfectionists
Batch Image Resizer - Resize, crop, shrink, flip, exif-rotate, convert, enhance, process multiple pictures and photos with professional software! 120+ Actions, 30+ Image Formats