Runs entirely on your local device. Your files never leave your device.
It depends on the preset. High Quality keeps images close to their original resolution and clarity. Balanced trades a small, usually unnoticeable amount of image quality for a meaningfully smaller file. Maximum Compression prioritizes the smallest possible file size, which can visibly soften embedded images.
Nowhere. Your files never leave your device — FormatGrid never uploads, transmits, or stores them on any server. All compression happens locally in your browser's memory and is discarded once you close or refresh the tab.
Standard tools upload your file to a remote server, process it in a queue, then send the result back — three network round-trips before you get anything. FormatGrid processes everything locally on your device's CPU the moment you select your file, so there's no upload, no queue, and no download wait.