- On Mac ImageOptim is a free and open-source app with a clean UI that uses the best command line optimization tools like MozJPEG and Pngcrush.
- I work there. It's a cloud-based image management system with endless features, from upload/storage, through a wide array of image manipulation options, to fast delivery via multiple CDNs. For image compressing, we have the full-auto mode, which selects the image format, quality and crops out the uninteresting parts, see http://cloudinary.com/blog/intro...You can create a free account easily on Cloudinary. I would recommend uploading high-res or lossless originals, then using w_[width],f_auto,q_auto to get scaled-down images that use the right image format for the particular image and browser (PNG, JPEG, lossy/lossless WebP if available, etc), at the right quality settings for the particular image so you get optimal compression without artifacts. You can use q_auto:eco to further reduce the file sizes, or q_auto:best if you're really picky about quality and want to bump it up.
- Despite what it may seem, Telegram is a spectacular productivity tool. It is possible to store in your profile all types of files and the application allows you to compress all kinds of jpg, mov, etc files In an excellent option at the same time that is very fast.
- If your use case is to deliver optimized images on the website or app, then you can try ImageKit.io - https://imagekit.io. The moment you start delivering images through ImageKit, it takes care of format selection, quality adjustments and smart cropping. Besides compression, it offers dynamic URL based resizing parameters and uses CDN for a faster delivery. We have seen people getting 30%+ reduction in page weight just by a mere host name change in the code.