TruePNG is described as 'is one of the most advanced PNG optimizers available. It does the most exhaustive checks for reductions, that lets it to optimize further, even if it uses a less efficient compression algorithm than others tools' and is an app in the OS & Utilities category. There are more than 25 alternatives to TruePNG for a variety of platforms, including Mac, Windows, Linux, Online / Web-based and SaaS. The best alternative is ImageOptim. It's not free, so if you're looking for a free alternative, you could try TinyPNG or PNGGauntlet. Other great apps like TruePNG are pngquant (Free, Open Source), Pingo Web Image Optimizer (Free), Oxipng (Free, Open Source) and OptiPNG (Free, Open Source).
ImageOptim is excellent for publishing images on the web (easily shrinks images “Saved for Web” in Photoshop). It's useful for making Mac and iPhone/iPad applications smaller (if you configure Xcode to allow better optimization).
TinyPNG uses smart lossy compression techniques to reduce the file size of your PNG files. By selectively decreasing the number of colours in the image, fewer bytes are required to store the data. The effect is nearly invisible but it makes a very large difference in file size!
Experimental, fast Web PNG/JPG optimizer which offer lossless, visually lossless or lossy compression. it performs image reductions over iterations thanks to recursive multi-processing and multithreading systems.
OptiPNG is a command-line PNG optimizer that recompresses image files to a smaller size, without losing any information. This program also converts external formats (BMP, GIF, PNM and TIFF) to optimized PNG, and performs PNG integrity checks and corrections.
PngOptimizer compresses graphics files and removes extra, unnecessary data without affecting quality. It will update PNG files or converting BMP, GIF or TGA files to the PNG format using simple drag-and-drop.
Leanify is a lightweight lossless file minifier/optimizer. It removes unnecessary data (debug information, comments, metadata, etc.) and recompress the file to reduce file size. It will not reduce image quality at all. Features