Compress PDF

Mail servers commonly stop at 10 or 25 MB, and application portals are often stricter still at 2 or 5 MB per file. A ten-page contract scanned at 600 dpi in colour can easily pass 40 MB, even though the content is just black text on white paper. The same thing happens with a report full of screenshots or a brochure exported straight from a design tool.

There are two modes here, and the difference between them matters far more than the size figures do. Light rebuilds and re-saves the file structure, which leaves the text as text, still selectable, copyable and searchable, in exchange for a modest saving; a PDF that is mostly text may come out barely smaller, which is normal rather than a failure. Strong re-renders every page to a JPEG at one of three quality levels, which cuts much deeper because each page becomes a picture of itself. That is also precisely what it costs you: after strong compression nothing on the page can be selected, copied or searched, and small type and thin lines go soft.

Strong is therefore a fair choice for a scanned brochure or a photo-heavy deck that only has to be looked at, and the wrong one for a contract somebody still needs to quote from or search. Neither mode can be undone, so keep the original if the document will be printed at full quality or read closely later. If light does not get you under the limit and the text has to survive, splitting the file with pdf-split is a better answer than reaching for strong, and if a page-image PDF already exists and has to be searchable, pdf-ocr can put a text layer back. The file is processed in your browser, so a confidential document never travels to a server to be made smaller.