- smush.it!: smush.it! makes optimization of your images a breeze. Created by Stoyan Stefanov and Nicole Sullivan, smush.it! is a tool that is available as a Firefox extension, a bookmarklet, or as a simple web-based application (hosted by Yahoo!).
- RIOT: RIOT – which stands for Radical Image Optimization Tool – is an image optimizer for Windows users that is available as a standalone application or as an extension of IrfanView. It supports inputs in JPG, PNG, and GIF files and has the ability to strip out image metadata for further reduction of file bloat.
- PNGOUT: Created by game programmer Ken Silverman, PNGOUT is a popular, free, and no-frills tool for lossless optimization of your images. PNGOUT can run in the command-line or Windows Run dialog box.
- Online Image Optimizer: The Online Image Optimizer from Dynamic Drive is a web-based tool for compressing your images further. You can either provide the link to the image you wish to optimize, or upload it from your local machine.
- SuperGIF: SuperGIF is a free utility for Windows and Mac OS users that optimizes your GIF images. It has an intuitive and simple user interface that allows for drag and drop interaction, and it can compress GIFs 50% more in some instances.
- PNGGauntlet: PNGGauntlet is a .NET GUI application for PNGOUT. It can be used to convert JPG, GIF, TGA, PCX, and BMP to highly optimized PNG files.
- PNGCrushrrr: PNGCrushrrr is a free GPL-licensed Mac OS utility for crushing down your PNG files to very small sizes. It has a drag-and-drop interface, allowing you to drag one or more PNG files into it, compressing the files and preserving the original file so you are able to compare the size difference.
- SuperPNG: SuperPNG is a free Photoshop plugin for saving significantly smaller PNG files compared to Photoshop’s native save feature for PNG’s. It also includes some advanced PNG-creation features such as 16-bit color support, variable compression, gamma correction, and metadata saving. Check out some PNG samples saved by SuperPNG in the PNG Samples page.