Forms often say "PDF must be under 200 KB". Choose your PDF, type the size you need, and the tool finds the best quality that fits. Your document stays on your device - it is never uploaded.
It redraws each page as a JPEG image at a lower resolution and rebuilds the PDF. When you give a target size it tries several quality levels and keeps the best one that fits under your limit.
No. The pages become pictures, so the text is no longer selectable. Use this for scanned documents and proofs that are only read or printed. If you need searchable text, keep the original file.
A PDF that is mostly text and already small is cheaper to store as text than as pictures. In that case the original is the better file. The tool tells you when this happens.
Then even the lowest quality is above the limit. Try the black and white option, split the PDF and remove pages you do not need, or ask whether a larger limit is allowed.
No. Everything happens inside your browser, so your documents never leave your device.