You have a folder of product shots or travel photos and a site that loads like molasses. Every "free" image compressor on the first page of search wants the same thing first: drag your pictures into a web form and wait while they upload to someone else's server. If the photos are client work, family pictures, or anything unlisted, that upload is a problem you never agreed to take on.
Doing it locally changes the math. With the Image Compressor you set a max width and a quality level, and the browser redraws the picture on a canvas and hands you a smaller file — JPEG or WebP — straight back to your device. The original never leaves the tab. No account, no size cap you didn't choose, no "processing" queue.
Format matters as much as size. WebP is usually smaller than JPEG for the same look, and PNG keeps sharp edges and transparency. If your export is the wrong shape, the Image Converter flips between PNG, JPEG, and WebP in a couple of clicks. Convert, then compress, and you get the smallest portable file for the job.
Why bother keeping it private? Because the moment a photo hits a third-party server you've lost control of where it goes, how long it's kept, and who else can see it. The whole point of an in-browser tool is that the work happens where the file already lives — on your machine.
Quick path: open the compressor, pick a max width around 1600px for the web, slide quality to ~75–80%, download. For PNGs that need to be smaller, convert to WebP first. You just shaved your page without uploading anything.