Scan to PDF without a scanner
The form someone wants back as a PDF by Friday, scanned with the phone in your pocket.
- Nothing is uploaded
- Works offline after first visit
- Open source
- No watermark · limit is your device’s memory; phones hold less
No scanner at home? Photograph each page with your phone and get one clean PDF with straight, white pages, ready to email or upload. 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.
Landlords, schools, HR departments and insurers still ask for signed paperwork back "as a scanned PDF", and most homes no longer have a scanner. A phone photo of each page, straightened and cleaned up here, is what they are asking for: one PDF, pages in order, white paper, black text.
A worked example: a three-page rental application you have filled in and signed by hand. Lay each page on the kitchen table, which is darker than the paper, and take a photo from above with all four corners in view. Drop the three photos here in order (IMG_2041 to IMG_2043); the previews show a green outline around each page it found. Black and white is already chosen, which makes typed text and pen ink crisp. Press Make PDF and you get scan.pdf, three pages at the usual paper size for where you live, ready to attach.
If a page outline is missing or wrong, retake that photo with more contrast behind the paper. For a document with colour that matters, such as a stamped certificate or a signature that must be blue, switch the look to Colour.
How it works
- Photograph each page on a darker surface, all four corners in view.
- Drop the photos in page order and check the outlines.
- Press Make PDF and send scan.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
Is a phone scan acceptable where a scanned copy is asked for?
Almost always: what matters is a legible, complete copy of every page. A straightened black and white page from a phone looks much like an office scan at normal viewing size.
What order do the pages go in?
The order of the list. Drop them in order or move them with the arrows before pressing Make PDF.
The PDF is too big for the upload form. What now?
Black and white pages are small already. If the form still refuses the file, run it through Compress PDF, or choose Grey instead of Colour.
Are the pages uploaded?
No. The photos are processed in this tab, so a signed application with your ID number stays on your device.
More PDF tools
Document scanner
A photo of a sheet of paper becomes a flat, white, straight scan, without a scanner app and without sending the page anywhere.
Image to PDF
Turn photos, scans and screenshots into a single PDF. One image per page, in the order you choose.
PDF to Image
Export every page, or just some, as JPG or PNG at the resolution you need. Rendered on your device.
Reorder & Delete Pages
See every page as a thumbnail, drag them into the order you want, remove the extras. Saved on your device.
Other conversions
Guides
- 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.