Caesium is one of the most popular image optimization software available helping photographers, bloggers, webmasters, businesses or casual users at storing, sending and sharing digital pictures.
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. Advanced users will find extra features, like metadata storing options or folder structure support.
Command Line Tool
If you are working on Linux or MacOSX and want to be geeky, you can use the Command Line Tools, which are the pulsing heart of Caesium. You can compress JPEG and PNG with advanced tools very quickly. It also works on Linux servers.
Just have a few bunch of images to compress and you don't want to download a dedicated software to accomplish the task? Do it online!