OpenDocScan

Most scanner apps charge a subscription to remove a watermark or lift a page limit, and many keep your documents on their servers. OpenDocScan does the whole job inside your own browser tab instead, so your scans never leave your device and there is nothing to pay for.

Point your phone at a page, or import a photo you already have. OpenDocScan outlines the sheet, and you can drag any of the four corners if the outline is off. It then straightens the perspective so the page comes back rectangular, and evens out shadows and warm lighting so the paper reads white and the ink reads black. Choose Photo, Enhance or Black & White, and adjust brightness and rotation.

Keep adding pages, reorder or delete them, then export a PDF in A4, US Letter, US Legal or the scan's own shape. Text recognition (English) runs on your device and makes the PDF searchable and selectable.

It is a progressive web app: add it to your home screen and it works offline. OpenDocScan is open source under MIT or Apache-2.0.