PngOptimizer comes to the free market as a rather unusual program that on the other hand performs useful tasks when it comes to PNG images. Within the simplest interface possible, this software has the capability to reduce the size of a PNG file, thus reducing used space on the hard disk.
It does that by cleaning any unnecessary information attached to that specific PNG image file. Other features include the possibility to transform BMP, GIF and TGA pictures into the PNG file format. PNG screenshots and APNG, which stands for animated PNG, are also supported.
For more advanced users, the command line version and the .dll version come handy.