In short
This tool reduces the size of a PDF, for example to stay within an attachment or upload limit. Most of the saving comes from the images: they are recompressed as JPEG and downsized according to the level you choose (light, recommended or strong), then the file structure is optimised. Text and vector drawings are left untouched: they stay sharp and selectable. With a target size in MB, the tool looks for the gentlest compression that reaches it, or delivers the lightest file possible. A PDF made mostly of text shrinks only a little. Several PDFs can be processed in one go, with the same settings, and are delivered in a ZIP. Everything happens in your browser.