PNGSquash is the easiest, most effective way to reduce the size of your PNG images. Per the PNG format, all compressions are done losslessly — i.e., with no change in quality — so it is ideal for web developers looking for essentially free bandwidth, app developers needing to save space, or anyone else looking to decrease the size of their images at no cost with a simple, one-time operation.

Features:

• Instead of using just one single PNG compressor (like most other competing apps), PNGSquash combines ALL of the top PNG compressors together (PNGCrush, OptiPNG, AdvPNG, and PNGOut*, respectively) to allow for maximum possible compression.
• Compresses images concurrently, taking advantage of every processor (or core) in your computer.
• Provides configurations for you to choose from, edit, or add depending on your needs (the defaults are “Light”, “Medium”, and “Brutal” — this means you have don't need to mess around with preferences every time you want to shrink the size of an image).
• A simple, clean and straightforward UI.

*PNGOut cannot currently be bundled due to licensing restrictions, but there is a preference to enable it if you have it installed.