RIOT - Radical Image Optimization Tool is described as 'Saving images for web/email/other media with the best compression ratio and quality is a difficult task if you don’t have the right tools. Choosing the right format then choosing the right parameters are the key factors of smaller files' and is a popular Image Optimizer in the Photos & Graphics category. There are more than 50 alternatives to RIOT - Radical Image Optimization Tool for a variety of platforms, including Windows, Mac, Online / Web-based, Linux and Wordpress. The best alternative is Caesium Image Compressor, which is both free and Open Source. Other great apps like RIOT - Radical Image Optimization Tool are ImageOptim (Free Personal, Open Source), FileOptimizer (Free, Open Source), XnConvert (Free Personal) and Squoosh (Free, Open Source).
Caesium Image Compressor lets you compress your pictures up to 90% without visible quality loss. Providing a simple yet effective interface with a real-time preview and multiple image processing at the same time, everyone will be able to reach the best result.
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).
Some users think ImageOptim is a great alternative to RIOT - Radical Image Optimization Tool, some don't.
XnConvert is an easy image converter for graphic files, photos and images available on Windows, MacOSX and Linux. It supports more than 400 file formats (jpeg, tiff, png, gif, camera raw, jpeg2000, WebP, OpenEXR, ...).
Compress and compare images with different codecs, right in your browser. Squoosh is an image compression web app that allows you to dive into the advanced options provided by various image compressors like OxiPNG, MozJPEG and JPEG XL.
Convert and Rename images in batch mode Support JPEG, BMP, GIF, PNG, TIFF and JPEG2000 Resize, crop, change color depth, apply color effects, add text, watermark and border effects Rename images with sequential number Search and replace texts in the file names...
Utilities for archiving photos for saving to long term storage or serving over the web. The goals are: use a common, well supported format (JPEG), minimize storage space and cost, identify duplicates / similar photos.