Sign a PDF by Drawing Your Signature in the Browser

Draw your signature on a pad with a mouse, trackpad, finger or stylus, choose where it lands, and pdf-lib stamps it onto the page. No account, no email round-trip, and no copy of the document on anyone else's system.

About the PDF Signature Tool

Add a PDF and a signature pad appears beneath it — a 560 by 170 canvas with a dashed border, drawn with a rounded 2.6-pixel stroke in dark navy rather than pure black, which reads more like ink than like a computer line. It listens for pointer events, so a finger on a phone, a stylus on a tablet and a trackpad on a laptop all work identically, and a Clear button lets you try again until the shape looks like your hand made it.

Three settings control placement: the page number, one of five positions — bottom right by default, plus bottom left, bottom centre, top right and top left — and a width slider running from 10 to 60 percent of the page width, starting at 28. The signature is inset 28 points from the page edges, and its height follows automatically from the proportions of what you drew, so it never stretches.

Key Features

  • Draw with whatever you have: The pad is driven by pointer events rather than mouse events, so touchscreens and pen input are first-class rather than an afterthought.
  • Transparent background: Only your strokes are written into the image, so the signature sits over the existing text and ruled lines instead of covering them with a white box.
  • Five placement positions: Bottom right, bottom left, bottom centre, top right and top left, each inset by 28 points from the edge of the page.
  • Width from 10 to 60 percent: The slider sets the signature width as a proportion of the page, so it scales correctly whether the document is A4, Letter or something unusual.
  • The rest of the file is untouched: pdf-lib opens the document, embeds the signature as a PNG and saves — the other pages, the text layer and the existing content are all left exactly as they were.
  • No signing service in the middle: There is no account to create, no link emailed to a counterparty and no copy retained by a platform, because the document is opened and written in your own browser.

How to Use the PDF Signature Tool

  1. Add the PDF you need to sign — the signature pad appears below it.
  2. Draw your signature on the pad, using Clear to start over if it comes out wrong.
  3. Set the page number, pick a position, and adjust the width slider until the size looks right.
  4. Press Sign and Download to get the file, saved with -signed added to its name.

How It Works

The pad canvas is exported as a PNG data URL and embedded into the document with pdf-lib, then drawn onto the page you chose at the width you set, with the height derived from the aspect ratio so the strokes keep their proportions.

Be clear about what kind of signature this produces. It is a drawn mark placed onto the page — an image of your signature, not a cryptographic one. There is no certificate, no key pair and no embedded hash, which means the file carries nothing that would let a recipient prove the document has not been altered since you signed it. Under the electronic signature rules in the US, the UK, the EU and Australia a drawn mark of this kind generally counts as a simple electronic signature and is accepted for a great many everyday agreements, but it is not an advanced or qualified signature, and anything requiring that standard — certain property, probate and regulated filings — needs a certificate-based tool instead. If you are unsure which category your document falls into, that is a question for whoever is asking you to sign it.

One practical note: each run places one signature on one page. To sign several pages, feed the signed file back in and repeat.

When You Need It

A freelance consultant receives an engagement letter setting out day rates and a client list. Returning it through a hosted signing platform means the rates, the client names and the counterparty all end up in a third party's records, retained under terms the consultant never negotiated. Signing it locally and emailing it back keeps the commercial detail between the two parties who agreed it.

Someone signing a settlement agreement at the end of a job faces the same problem more sharply. These documents almost always carry a confidentiality clause covering their own contents, and uploading one to a free web signer to add a signature sits awkwardly with a term you are about to agree to. The signature goes on in the browser and the file never moves.

FAQ

Frequently Asked Questions

Is this a legally binding signature?
In many contexts a drawn electronic signature is accepted, and both the US ESIGN Act and the EU eIDAS framework recognise simple electronic signatures for a wide range of agreements. What this tool produces is that simple tier: a picture of your signature placed on the page, with no certificate proving who applied it or that nothing changed afterwards. For documents that specifically require an advanced or qualified electronic signature, you need certificate-based software. Ask the party requesting the signature which standard they need.
Can I sign more than one page at once?
Not in a single pass — the page number field takes one page and the signature is placed there. For a contract needing initials on every page, run the tool repeatedly, feeding the signed output back in each time and changing the page number. The file is rewritten cleanly each time, so there is no accumulating damage from doing this.
Will there be a white box around my signature?
No. The pad looks white because of its styling, but the underlying image only contains the strokes you drew, and everything else stays transparent. When it is embedded, the ruled signature line and any text underneath show through normally.
Does my contract get uploaded so it can be signed?
It does not. pdf-lib runs inside this page and is served from this domain, so the document is read from your disk into browser memory, has the signature image drawn onto the page you selected, and is written straight back out as a download. Nothing is emailed, nothing is stored, and there is no counterparty portal holding a copy — which is the substantive difference between this and a signing service.
My signature came out too big or in the wrong corner.
Nothing has been altered until you download, so adjust the width slider or the position and run it again. If you have already downloaded a version you do not want, discard it and sign the original again — the tool always works from the file you added rather than from its own previous output.
Can I reuse the same signature on another document?
The pad clears when you start fresh, so you will draw it again. That is a deliberate consequence of storing nothing: no signature image is kept in the browser or anywhere else between sessions. If you need a consistent mark, sign once, keep the resulting PDF, and reuse that page.
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