Petfinder's photo rules are generous in one direction and strict in another. Files can be JPG, PNG, GIF or BMP up to 25MB, so size rarely blocks an upload — but the listing only looks good if the photo is at least 570 pixels wide, and each pet gets six media slots (six photos, or five photos and one video), with the primary photo carrying the search results. That combination is exactly where rescues lose time: twenty animals, twenty folders of 5MB phone shots, and a 25MB ceiling that never fires while the pages still load slowly. Pre-sizing the photos to 1000-1200px wide and compressing to a few hundred kilobytes gives you a listing that uploads fast, keeps detail at the 570px floor, and leaves room to fill all six slots. Skwish compresses and resizes in the browser with a per-file readout and a ZIP export, so a full intake batch goes through in one pass. Nothing is uploaded to a server.