Scanned books and academic papers waste enormous amounts of screen space on margins, which matters most on the small screens where you'd actually want to read them.
Drag a crop box over the page, apply it to one page or the whole document, and download. You can also enter exact measurements if you're matching a print specification, and there's an auto-detect option that finds the actual content bounds and trims to them.
Cropping is also how you rescue a scan that came out with a black border, or split a page that was scanned as a two-page spread. Since it changes the visible area rather than re-drawing anything, it's lossless and instant — the text stays selectable and the file doesn't grow.
Combine files into one PDF and set the order before you merge.
Break a document into separate files by range or interval.
Drag pages into a new order, rotate or drop the ones you don't need.
Turn sideways or upside-down pages the right way up.
Pick pages to drop, visually or by range.
Keep only the pages you want as a separate file.
Combine JPG or PNG images into one PDF, with page size control.
Render pages to images at the resolution you choose.
Shrink a PDF with a side-by-side quality preview and a size target.
Add a searchable text layer to a scanned document.
Extract text as plain text or Markdown, in reading order.