Free phone document scanner: scan to PDF in your browser
Take a photo of each page with your phone, or pick photos you already have. The scanner finds the edges of the page, straightens it, removes shadows and turns it into a clean PDF you can download or send as a fax. Free, no app and no sign-up, and nothing is uploaded: everything happens on your device.
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Page look
Nothing is uploaded. Your photos are processed on this device, in your browser.
Photograph each page, or pick photos you already took
Lay the page on a darker surface, in even light, and fill most of the frame with it. You can also drop photos here.
How this works
Everything below runs in your browser, in plain JavaScript; the heavy steps run in a background thread so the page stays responsive. These are the actual steps, including where they can go wrong.
- Opening the photo
- The photo is turned upright using the orientation your camera saved with it, and scaled down to at most 2,400 pixels on its long side. That is more detail than a 200 dpi Letter page needs, and it keeps phones from running out of memory with several pages.
- Finding the page
- A copy about 512 pixels across is made. Each pixel gets a 'paper' score: its brightness minus part of its colour saturation, so white paper stands out from wood or fabric. After a blur, Otsu's method picks the cut between paper and background, and the largest bright area is taken as the page. Its outline is reduced to the four corners that enclose the most of it.
- Sharpening the edges
- Along each side of the page, the tool looks across the edge for the strongest change in brightness (a Sobel gradient), fits a straight line through those points and takes the corners where the lines meet. This works best for a light page on a darker surface.
- When it isn't sure
- A confidence score combines the page's size in the photo, how completely it fills the four-sided shape, the corner angles, how much of the outline sits on a real edge, and the contrast with the background. When the score is low, the corner editor opens so you can place the corners yourself, or use the whole photo.
- Straightening
- The four corners are mapped onto a US Letter page with a perspective transform (a homography, solved from the four point pairs). Every pixel of the 1,700 by 2,200 pixel output (200 dots per inch) is traced back into the photo and blended from its four nearest pixels.
- Cleaning up
- The paper's brightness is estimated in small blocks across the page and divided out, so shadows and uneven light turn white instead of grey. Black and white then marks a pixel as ink when it is clearly darker than its surroundings or dark outright, which keeps pencil and light pen visible. Grayscale and colour get the same shadow fix and a gentle contrast boost.
- The PDF
- Each page becomes one Letter-size PDF page. Black and white pages are stored as true 1-bit images, which keeps a page small and is what a fax machine prints anyway; grayscale and colour pages are stored as JPEG.
Limits: a white page on a white table, a page that fills the whole photo, or a strong shadow across the page can confuse the edge finder; the corner editor is there for those. A curved or folded page is straightened only at its corners, so curves stay curved. Every page is fitted to Letter size, so a receipt or card will look stretched.
Questions
Is anything uploaded?
No. Your photos are opened, straightened and cleaned by your browser on your device, and the PDF is created there too. Nothing is sent to FaxUp or anyone else, and the pages are gone when you close the tab. If you choose to send the scan as a fax, the PDF is uploaded at that point, on the send page, as part of sending it. Our analytics record that the scanner was used and how many pages, never the images.
Does it work on iPhone and Android?
Yes. It runs in Safari on iPhone and in Chrome on Android, with no app to install. "Take a photo" opens the camera; take one page, then tap "Take another photo" for the next. You can also pick photos you already took, including several at once. On a computer, choose or drop photo files.
How do I get a good scan?
Lay the page flat on a surface darker than the paper, such as a table or desk. Use bright, even light, and avoid your own shadow by holding the phone slightly to the side. Keep all four corners in the picture with a little background around them, and hold the phone roughly parallel to the page. Turn off the flash if it makes a glare spot.
What if it finds the wrong edges?
Tap "Adjust corners" on the page and drag each corner onto the corner of the paper; a magnifier shows the spot under your finger. If the photo is already just the page, tap "Use whole photo". The corner editor opens by itself when the tool is unsure.
Which mode should I choose?
Black and white is best for text, forms and signatures, and for faxing: it gives the smallest file and is what a fax machine prints. Grayscale suits pages with pencil shading or photos. Colour keeps stamps, highlighter and coloured ink, at a larger file size. You can switch at any time and every page is redone.
Is it really free?
Yes. Scanning and downloading the PDF are free, with no sign-up and no watermark. Sending a fax is a separate, paid service: "Send this as a fax" opens FaxUp's send page with your PDF already added, and you see the price there before you pay.
Can I fax the scanned PDF?
Yes. The PDF is Letter size at 200 dots per inch, close to the 204 by 196 dots per inch of a Fine fax, so text stays sharp. Use "Send this as a fax" to send it with FaxUp, or download it and send it any way you like.
Need to fax it?
Scan your pages above and tap "Send this as a fax", or upload any PDF or photo on the send page. Enter the fax number and follow the status until it is delivered. You pay per fax, any number of pages. Not sure how it will print? Check it first with the fax preview.
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