MicroPNG

MicroPNG is a powerful PNG image compressor, sometimes capable of reducing an image's file size by even 70%. Simply drag & drop your PNG files and MicroPNG will do its magic.

Works on Windows and Mac OSX. Requires Java to be installed. Simply double-click the downloaded .JAR file.

Official support website: http://jvemon.com/software/micropng/

Contact for support: http://jvemon.com/contact/