Caesium Image Compressor lets you compress your pictures up to 90% without visible quality loss. Providing a simple yet effective interface with a real-time preview and multiple image processing at the same time, everyone will be able to reach the best result.
XnConvert is an easy image converter for graphic files, photos and images available on Windows, MacOSX and Linux.
Oxipng is a multithreaded lossless PNG compression optimizer in Rust. It can be used via a command-line interface or as a library in other Rust programs.
Phatch is an user friendly, cross-platform Photo Batch Processor and Exif Renamer with a nice graphical user interface. Phatch handles all popular image formats and can duplicate (sub)folder hierarchies.
Last code commit in 2010, latest release from 2014.
PhotoZoom Pro not only creates larger images than any other software (up to 1 million by 1 million pixels), it also produces higher quality results. PhotoZoom Pro is equipped with S-Spline Max, a unique, award-winning image resize technology which excels at preserving clean...
Leanify is a lightweight lossless file minifier/optimizer. It removes unnecessary data (debug information, comments, metadata, etc.) and recompress the file to reduce file size. It will not reduce image quality at all.
With BIMP you can apply a set of manipulations to an entire group of images! It provides an easy to use interface and a lot of batch functions: