Graphical interface for Zoopfli, PngOut and OptiPng. Reduces the size of PNG images without sacrificing the quality applying in sequence the three tools.

Zopfli Compression Algorithm was created by Lode Vandevenne and Jyrki Alakuijala, based on an algorithm by Jyrki Alakuijala; its open source code is on https://github.com/google/zopfli
PngOut was created by Ken Silverman: http://advsys.net/ken/utils.htm
OptiPng is licensed by Cosmin Truta and the Contributing Authors: http://optipng.sourceforge.net/