Deskew a PDF: straighten crooked scans

Rotate turns a page in 90-degree steps, which is what a PDF can record directly and what fixes a page that went through the scanner sideways. Deskew corrects the small tilt — a degree or two — that a sheet picks up in the feeder. That angle cannot be recorded in the file, so correcting it means re-rendering the page, which is why the two are separate tools with quite different costs.

Because straightening one would make it worse. Correcting a tilt requires re-rendering the page as an image, permanently removing its text layer, its annotations and its crisp type. A born-digital PDF is not tilted — its text sits on exact baselines — so there is nothing to gain. If its text does sit at an angle, that is a design choice such as a rotated stamp, and rasterising the page to level it would be a poor trade.

By the one thing every document reliably has: horizontal lines of text. It sums the dark pixels in each row of the page at a range of candidate angles, and picks the angle where those sums are sharpest — where the lines stack into tight peaks with clear gaps between them. A tilted page smears each line across many rows and flattens that pattern.

No. The file is opened, processed and saved back by code running in this browser tab — there is no upload endpoint on our servers to send it to. You can watch the Network panel in your browser's developer tools while you work and confirm nothing carrying the document leaves the page.

Deskew is free, with no account required and no page or file-size caps imposed by the plan. Corrected pages become images, so run OCR afterwards if you need them searchable.

Yes. Once the page has loaded, every tool keeps working with the network disconnected, because the processing never depended on a server round-trip. AI features that use an on-device model need one download the first time; after that they run offline too.