I needed to sign a PDF one day and did what I always do - photographed my signature, opened it and the PDF in Photoshop, set the layer to Multiply, positioned it and exported as PDF. Got me thinking: why can't I do this in the browser? Client-side? So I built it and published it in case anyone else has the same problem. Free of course. A bit on how it works for the curious: you can draw the signature, type it, or upload a photo of your real one on paper. The photo route is what I use - it just looks like my actual handwriting. To remove the paper background, the code samples the local paper brightness across a grid in the image and compares each pixel to its local background, so uneven lighting in the photo doesn't throw it off. Anything above an adjustable threshold goes fully transparent, with a soft falloff so the ink edges stay clean. When the signature gets stamped onto the document, it's drawn with a multiply blend - same math as the Photoshop trick from the start of this comment, just running in the Canvas API. For PDFs the document is rendered with PDF.js and edited with pdf-lib, both loaded from cdnjs. JPGs and PNGs are just Canvas API, no library needed. You can also add text, dates, initials, and reposition everything. Hit the button, file downloads. The document itself never leaves your browser. No upload step, no server processing it, no accounts, no tracking. The only thing the page fetches from outside are those two JS libraries at page load. It's part of https://vajba.com where I build small browser tools I wanted to exist. No premium tier. No paywall. Happy to answer questions about how anything works under the hood. Especially curious if anyone finds a PDF it can't handle - or a signature photo the background removal struggles with.

Add Signature

Sign documents with your real signature, in your browser

Sign documents with your real signature, in your browser