Scan documents with your phone camera
A photo of a sheet of paper becomes a flat, white, straight scan, without a scanner app and without sending the page anywhere.
- Nothing is uploaded
- Works offline after first visit
- Open source
- No watermark · limit is your device’s memory; phones hold less
Turns phone photos of documents into a clean, straightened PDF by finding the page, flattening it and lifting shadows. It is free, needs no account and adds no watermark, and your files are not uploaded: everything runs in your browser on your device. The size limit is your device’s memory, and phones hold less; give the page a short while after one visit to save itself for offline use, and then it works offline.
Done
Open the network tab. Your files never appear in it.
Add files and run the tool to see every request this tab makes.
Your files are processed on this device and never sent to a server. Reload the page to clear everything from memory.
How it works
- Photograph each page flat on a darker table, with all four corners in the picture, then drop the photos here in page order. On a phone, choose the camera or your photo library.
- Check the green outline on each preview, pick a look (Black and white is crispest for typed pages) and choose one PDF or separate images.
- Press Scan. Each page is straightened to a rectangle, the paper turned white and the pages put into one PDF.
In your browser, not on a server
Your browser decodes each photo (HEIC too) in the tab. A 400-pixel copy is blurred, split into light and dark with Otsu’s threshold, and the largest light region is taken as the page if it fills its own four-cornered outline; its corners are the extremes along the two diagonals. A perspective transform (a homography solved from the four corners) maps every pixel of the flat page back into the full-resolution photo, capped at 3508 pixels on the long side (A4 at 300 dpi). The paper’s brightness is then estimated in coarse blocks and divided out, which turns shadows and yellow light white. pdf-lib (MIT) puts the pages into one PDF.
Compared with upload-based tools: Scanner apps want an account, a subscription or a watermark on free scans, and many upload every page to their cloud to process it. Here there is nothing to install, the pages are processed on your device, and the result is a plain PDF or image with no watermark.
Verify it yourself. Give the page a short while after one visit to save itself for offline use, then turn off Wi-Fi or switch to airplane mode and run the tool again. Or open your browser's developer tools (F12, or Cmd-Option-I on a Mac), pick the Network tab, and watch it while you convert. The panel above does the same count for you.
Questions
How is this different from just putting the photo in a PDF?
A photo shows the table around the page, the page is a trapezoid because the phone was at an angle, and the paper is grey or yellow with a shadow of your hand. This cuts the page out, pulls its corners back into a rectangle and divides out the uneven light, so it looks like it came off a flatbed scanner.
What if it cannot find the page?
Then the whole photo is kept and cleaned up, and the note says so. Detection needs the paper to be lighter than what it lies on and all four corners in view: white paper on a white desk, or a page cut off at the edge, cannot be found. Take the photo again on a darker surface.
Can I search the text in the scan?
Not yet: a scan is a picture of the words. Run the PDF through OCR PDF next, which reads the text on your device and makes the PDF searchable.
Are my documents uploaded?
No. The photos are decoded, straightened and saved in this tab. IDs, contracts and medical forms never leave your phone or computer.
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- A free CamScanner alternative with no watermarkCamScanner's free account has storage and feature limits, with a Premium plan above it. Here is a scanning alternative with no watermark and no tier to pay for.
- How to scan a document with your phoneBoth iPhone and Android can scan paper into a clean PDF without a dedicated app, if you know where to look. Here is where, plus a browser option for when you would rather not.