PDF Deskew — what it does
Straightens scanned pages that were fed into the scanner slightly crooked. The tilt angle is detected on-device and each page is rotated by that small amount, which is the difference between a scan set you can read comfortably and one you keep tilting your head at.
How to use PDF Deskew
- Open the scanned PDF and review the pages — tilts are usually visible in the thumbnail grid.
- Run deskew; the tool measures the skew of each page and rotates it to level.
- Compare a page before and after in the preview.
- Export the straightened document.
Worked example: 60 vouchers photographed on a desk
Vouchers photographed with a phone app come in with each sheet at a slightly different angle. Deskewing levels the text baseline across the set, which is what makes a later OCR pass reliable — a tilted page is one of the most common reasons a scanned PDF extracts as gibberish.
At a glance
| Fixes | Small rotational tilt, typically a few degrees |
|---|---|
| Detection | Skew angle measured per page, on-device |
| Typical use | Phone-scanned receipts, vouchers, printed forms |
| Order of operations | Deskew before running OCR, not after |
| Limit | It corrects rotation, not perspective — a page photographed at an angle needs a scanner app's perspective fix |
Frequently asked questions
- What is PDF Deskew?
- Automatically straighten tilted scanned PDF pages — the skew angle is detected on-device and each page is rotated to fix it.
- Is PDF Deskew free to use?
- Yes — PDF Deskew is free to use, with no sign-up, no install and no account.
- Does PDF Deskew upload or store my data?
- No — PDF Deskew runs entirely in your browser, so your text, files and results never leave your device.
- Do I need to install anything to use PDF Deskew?
- No — it works in any modern browser (Chrome, Edge, Firefox, Safari) with no downloads, accounts or plugins.
- Does deskewing help OCR accuracy?
- Yes, substantially for small tilts. Text recognition expects roughly level baselines, so straightening first is the cheapest accuracy gain available before PDF & Image OCR.
- Will it rotate a page that is already straight?
- The measured angle is applied as a correction, so a page that is already level gets a no-op change. Skew is measurement-based rather than a fixed rotation.