GifJif - Turn GIFs into masterpieces.
DVDVideoSoft Image Convert and Resize - Free Image Convert and Resize is a compact yet powerful program for batch mode image processing.
Giphy - Search all the gifs and make your own animated gif
ImBatch - ImBatch is a batch image processor with a nice graphical user interface.
GifLab - The easiest way to create GIFs on your iOS device
Caesium Image Compressor - Compress your pictures up to 90% without visible quality loss.