Server-based compressors upload every file, wait in a queue, process, and download. A batch of 50 phone photos is 200 MB of upload before anything happens. Here the photos never leave the device, so the batch starts immediately and finishes as fast as your processor allows. On a modern phone that is about a second per photo.
Change the preset while a batch is loaded and every file is reprocessed. Click any thumbnail to check the result, drag to adjust its crop if a ratio preset is used, and download the ZIP when you are happy.
Try it on your own photoDrop a photo at the top of the page. Ten seconds later it's sized, sharpened and ready to post.
Compress a photo