libpng is a collection of routines used to create and manipulate PNG format graphics files. The PNG format was designed as a replacement for GIF and, to a lesser extent, TIFF, with many improvements and extensions.

PNG reference library (originally called pnglib). It is a platform-independent library that contains C functions for handling PNG images. It is developed by Guy Eric Schalnat, Andreas Dilger, Glenn Randers-Pehrson and others. libpng is dependent on zlib.