- Drag it in, choose it, or paste it. It is read here in the tab and never uploaded.
- The settings column holds 2 controls for this tool. The defaults suit most files.
- “Compress” works on your device, then Original and Result sit side by side with a download.
About Compress PDF
Compress PDF makes a document smaller by scaling and re-encoding the images inside it, at one of three levels, while leaving the text and vector art exactly as they were.
Almost all the weight of a large PDF is pictures, and almost all compression is a decision about them: how far to scale them down, and how hard to re-encode what is left. The three levels are that pair of numbers. Best quality keeps images generous and re-encodes them gently. Balanced is the one to try first. Smallest file scales aggressively and will show on photographs.
Everything that is not a picture is deflated losslessly — the text, the fonts, the vector art, the structure — so the words on the page are never touched, at any level. A page of pure text compresses barely at all, because there was nothing heavy on it to begin with.
Two rules keep the tool honest. An image that is already small enough is left alone rather than re-encoded for nothing, and if the result comes out larger than the original, the original is handed back with a note saying so. A PDF that has already been through this does not get smaller by going through it again.