A.I. Gigapixel - AI based image resizer
Ralpha Image Resizer - High-speed image batch conversion tool
waifu2x - Online/Offline tool to upscale images
ImBatch - ImBatch is a batch image processor with a nice graphical user interface.
Photozoom Pro - BenVista PhotoZoom Pro 7 creates perfect image enlargements and increases photo resolution at high quality using our patented S-Spline Max interpolation algorithm
Caesium Image Compressor - Compress your pictures up to 90% without visible quality loss.