The three steps
- You upload a PDF. StampMyPDF reads it directly in your browser using an open-source PDF library. It's never sent to a server — there isn't one to send it to.
- You photograph or upload your signature. Sign your name in dark ink on plain paper, snap a photo (or upload one), and crop down to just the signature. StampMyPDF then looks at every pixel: anything close to white becomes transparent, anything dark stays — so the paper disappears and only your signature is left.
- You drag it into place and download. Position and size the extracted signature on the page, pick black, blue, or red ink, adjust the pen thickness, and hit download. Your browser builds the finished PDF right there and saves it to your device.
Why "runs in your browser" actually matters
Most online PDF tools work by uploading your file to a server, processing it there, and sending it back. That's normal, and usually fine — but it means your document and your signature both pass through someone else's computer along the way.
StampMyPDF skips that step entirely. The PDF library and the image-processing code are loaded into your browser once, and everything — reading the PDF, removing the signature's background, placing it, and generating the final file — happens on your own machine. Open your browser's developer tools and watch the network tab while you use it: no file ever leaves.
What the background removal is doing
When you photograph a signature on paper, the file is really just a grid of colored dots. StampMyPDF measures how light or dark each dot is. Past a brightness threshold, a dot is treated as "paper" and made invisible; below it, the dot is treated as "ink" and kept. A short blend zone at the edge keeps strokes looking smooth instead of jagged. The "background cutoff" slider lets you move that threshold yourself if your photo has shadows or uneven lighting.