Online document scanner - scan with your phone to PDF

A photo of a page taken at an angle shows it as an irregular quadrilateral. From the four corners you mark, the tool computes a homography (the transform that maps that quadrilateral onto a rectangle) and resamples every output pixel from the matching spot in the photo with bilinear interpolation. Text lines come out straight and the page fills the frame. The corners can be placed in any order; they are sorted automatically, and the tool warns you if the lines cross.

The scan size follows the lengths of the marked sides, capped at 3508 px on the long side. That is A4 at 300 DPI, enough for printing and for most online forms.

In the PDF, black & white pages are stored losslessly (PNG) and colour or greyscale pages as JPG at 85% quality. Each page goes on its own A4 sheet, portrait or landscape depending on the scan.

• Use a contrasting background. A white page on a dark desk makes the corners easy to mark.
• Use even light. Daylight from the side works best; turn off the flash, which leaves a glare spot in the middle.
• Hold the phone parallel to the page. The smaller the angle, the sharper the text after straightening.
• Keep the whole page in frame, with a small margin of background around it.
• Tap the text on screen to focus before taking the photo.

To make the scan searchable, run it through OCR PDF or copy text from a single photo with image to text. To combine it with other files, use merge PDF.

Photos of your documents are never uploaded. Straightening, scan modes and PDF creation all run in the browser. The “In-browser camera” button asks for camera permission; if you refuse, the page is not on HTTPS or the device has no camera, you can still add pages with “Take a photo with your phone”, which opens the system camera app, or from files (JPG, PNG, WebP, HEIC).