libpng is described as 'is the official Portable Network Graphics (PNG) reference library (originally called pnglib). It is a platform-independent library that contains C functions for handling PNG images' and is an app in the Development category. There are five alternatives to libpng for Linux, Mac and Windows. The best alternative is libjpeg-turbo, which is both free and Open Source. Other great apps like libpng are libspng (Free, Open Source), GIFLIB (Free, Open Source), libjpeg (Free, Open Source) and libtiff (Free, Open Source).