EWWW Image Optimizer
The original plugin that started it all, the EWWW Image Optimizer can use freely available optimization tools directly on your web server OR use the Compress API + our Easy IO CDN to compress & resize JPG, PNG, and GIF images as well as optimize SVG & PDF files. Available on GitHub and WordPress.org.
DownloadSWIS Performance
Now you can get all the speed boosting tools that I use personally, in one handy package. Includes page caching, JS/CSS optimization tools, ability to disable unused JS/CSS, Google Font optimizer, CDN rewriter, and more.
Get SWISS3 Image Optimizer
A plugin for WordPress that lets you optimize all your images in all your Amazon S3 buckets. Works with multiple S3-compatible storage and integrates with EWWW Image Optimizer to provide full compression capability.
DownloadSILO
The Standalone Image Optimizer lets you optimize your images from the command line with no dependencies on WordPress. Read more about it at GitHub.
Get SILO