The simplest way to put a signature on a PDF

You get a contract as a PDF and need to add one signature before sending it back. Until now that meant buying a PDF editor, printing and rescanning the page, or uploading a confidential document to a website you'd never heard of.

StickPDF is a fourth option. Open the PDF in your browser, drop your signature image where you want it, download the new PDF. Your file never leaves your device while you do it.

What "never uploaded" actually means

Most online PDF tools send your file to a server, process it there, and send a result back. Along the way your contract sits on someone else's disk, and you have only a sentence like "files are deleted after one hour" to go on.

StickPDF reads the PDF, composites your images, and writes the new file entirely in JavaScript inside your browser. The server's only job is to deliver the web page itself.

Check it for yourself: open your browser's developer tools (F12), watch the Network tab, and load a PDF — nothing carrying your file goes out. Or load the page and then disconnect from the internet; the tool keeps working.

Features

Three ways to add an image — drop it onto a page and it lands exactly where you released it, paste a screenshot with Ctrl+V, or use the "+ Add image" button on any page.
White background removal — turn the white paper behind a scanned signature transparent so it sits naturally on the document. One click puts it back if you don't like the result.
Position and size — drag to move, pull the corner handle to resize with the aspect ratio locked.
Copy once, place many times — Ctrl+C then Ctrl+V duplicates a signature with its background edit intact, across as many pages as you need.
Works on your phone — open a PDF from an email attachment, sign it on the spot, and save.
Transparent PNGs stay transparent — alpha channels are preserved in the exported PDF.

How to use it

Open a PDF — click "Open PDF" or drag the file into this window.
Add your image — drop your signature or stamp onto the page, right where it belongs.
Fine-tune — click the image and a toolbar appears at the bottom: remove background, copy, duplicate, delete.
Download — click "Download PDF" to save the merged file. Your original stays untouched.

Frequently asked questions

Are my files really never uploaded?

Yes, really. You can confirm it in your browser's Network tab, and the tool keeps working after you disconnect from the internet. That also means the site operator cannot know which documents you opened.

Which image formats can I use?

PNG and JPG. Prefer PNG if you plan to remove the background — JPG compression leaves faint artefacts around the edges of white areas, which makes background removal look dirty.

I don't have a signature image. How do I make one?

Sign on clean white paper and scan it at 300–600 DPI, saving as PNG — that gives the cleanest result. A phone photo works too, but shoot in bright, even light so no shadow falls across the paper, or background removal will leave grey patches. See the scanning guide for details.

Is a signature added this way legally binding?

Placing an image is a visual mark and carries no guaranteed legal effect on its own. What counts as a valid signature depends on the applicable law, the type of document, and what the parties have agreed. For anything consequential, check with a qualified professional.

Is it free?

Yes, and there is no signup. Running costs are covered by advertising on the site.

How do I put the same signature on several pages?

Select the image you've already cleaned up, press Ctrl+C, scroll so the target page is on screen, and press Ctrl+V. The duplicate keeps the background edit.