Rotate PDF

Every page can carry a /Rotate entry — 0, 90, 180 or 270 degrees clockwise — that tells a viewer how to display it (ISO 32000-1 §7.7.3.3). The page content itself stays as drawn. This page reads each page's current value, computes the new one, and writes it back; nothing is rasterised or re-encoded, so quality and size are unchanged apart from the rewrite.

“Turn by” adds the angle to the current value (a page already at 90° turned by 90° becomes 180°); “Set to” makes every selected page exactly that angle. The table shows now → after for each page and greys out pages that would not change; if none would, no download is offered. Odd/even follow the viewer's page numbers, not printed folios.

A page whose stored rotation is not a multiple of 90 (rare, non-conforming) is rounded to the nearest quarter turn and flagged. A password-protected PDF is refused. The reading and writing is done by pdf-lib, an open-source (MIT) PDF library that is downloaded to your browser only when you choose a file — the page itself stays small. Nothing leaves the browser: the file is read into memory on your device, rewritten there and offered back as a download; the same four anonymous usage counts as the rest of the site apply.