Rescale a finished book interior PDF to a KDP paperback or hardcover trim size without reflowing the text, so page count and line breaks stay the same. Add 0.125 in bleed, match margins to KDP minimums, then run a preflight that checks page size, page count, text, image resolution and blank pages. Runs in your browser: the PDF is never uploaded. Free, no sign-up. Interiors only, up to 100 MB.