Sign PDF

Draw your signature and place it on any page. Free, no upload. 1 GB max · Up to 1 GB · Processed locally, never sent to a server.

A lease to send back, a quote to approve, a form due before the end of the day: the usual route is to print the document, sign it with a pen, scan it and send it out again. Sign PDF removes the last three steps by putting your mark straight into the file, with no printer within reach and no application to install.

You draw your signature in a pad measuring 560 by 160 pixels, with a mouse, a finger or a stylus. The stroke is then cropped on its own: the tool sweeps the pixels to find the edges of what you drew, leaves six pixels of padding, turns the resulting rectangle into a PNG with a transparent background, and has pdf-lib embed it in the page you named.

The rest of the document is left alone. pdf-lib opens the file, adds an image to one page and saves again: text stays text, the other pages are untouched, nothing is converted to a picture. What you get is your original PDF with a stroke laid on top of it, which is the exact equivalent of a scan of a signed document, minus the printer and the scanner.

How to use it

  1. Load the document to sign The PDF has to be readable without a password: pdf-lib refuses encrypted files and the tool then reports that the file could not be read.
  2. Draw your signature The white pad responds to mouse, finger and stylus. The stroke is 2.4 pixels thick, in ink blue. The clear button underneath wipes the pad back to empty.
  3. Give the page number One pass signs one page. A number larger than the page count is brought back to the last page instead of being rejected.
  4. Set the position and the size Six anchors are offered: three along the bottom, left, centre and right, two at the top, left and right, plus the centre of the page. The width is 140, 190 or 260 points, placed 36 points from the page edge.
  5. Download the signed file The result is named -signe.pdf and the note recalls which page was signed. To initial a second page, drop that file back in and go round again.

A drawn signature and an electronic signature are not the same thing

This tool produces an image of your mark, laid on a page. It does not produce an electronic signature in the sense of the European eIDAS Regulation, Regulation (EU) No 910/2014, and the difference is not merely a matter of vocabulary.

An advanced or qualified electronic signature rests on a certificate issued to an identified person, on a cryptographic hash of the document and, most of the time, on a timestamp. The file then carries proof that it really was you who signed and that not one byte has moved since. A reader displays a validity banner and names the certification authority.

None of that applies here. The embedded PNG is tied neither to your identity nor to the content of the document: anyone can extract it, move it, copy it onto another PDF, and no later modification will be flagged. We are at the level of a simple electronic signature, which eIDAS forbids anyone to deny legal effect on the sole ground that it is electronic, but only the qualified signature is presumed equivalent to a handwritten one. In the United States, the ESIGN Act and UETA follow the same logic: a signature is not void merely for being electronic. Either way, if the signature is contested the burden of proof falls on you. For a quote, a purchase order or a letter confirming an address, this is common practice; for a deed, or any document where a qualified signature is explicitly required, you need a trust service provider.

How the stroke is placed on the page

Coordinates are computed in PostScript points, the internal unit of the PDF format, at 72 points to the inch. The 36 point margin therefore leaves exactly half an inch, a little over a centimetre, between your signature and the edge, whatever the paper size, and the medium width of 190 points comes to about 6.7 cm, or 2.6 inches.

The width you choose is applied as it stands and the height follows from it, the tool keeping the proportions of the cropped rectangle. A wide flat stroke gives a low band; a compact mark fills something closer to a square. If your signature comes out too big, redraw it using more of the pad’s width rather than reaching for the size setting.

The coordinate origin of a PDF page is the bottom left corner, which explains how the anchors behave: the bottom positions are measured from the foot of the page, the top ones by subtracting the height of the image. On a landscape page everything follows automatically, since the tool reads the real dimensions of the page you targeted.

What the tool does not do

It does not fill in form fields. If your PDF carries an interactive signature field, the stroke will be laid over it rather than inside it: the field stays empty as far as any software that inspects it is concerned.

It does not initial every page for you. For a contract that wants your initials at the foot of each sheet, the file has to go through once per page, which stays workable but gets long beyond a few pages. Nor does it add a date, a place or a wording of the “read and approved” kind: if your document calls for those, draw them yourself in the pad.

Frequently asked questions

Is my signature stored anywhere?

No. The stroke lives in a canvas on the page and disappears the moment you close the tab or clear the pad. It is not remembered for a future visit, which does mean redrawing it each time, but also means no facsimile of your mark is left sitting in a store.

Why is my stroke cropped automatically?

The tool walks the pixels of the pad to find the bounds of your signature, with six pixels of padding, and embeds that rectangle only. Without the crop, a mark drawn in one corner would arrive lost in the middle of a large empty space.

Can I sign several pages in one go?

No, each pass handles a single page. Sign the first one, download the result, drop it back in and give the next page number: the file gains one more mark on each round.

Can the signature be taken out of the document?

Yes, by anyone with a PDF editor. The image is an ordinary page object, not a seal. That is the main limitation of this kind of signature, and the reason why high-stakes documents call for a certificate.

My PDF is refused when I load it, why?

Two situations produce the read error: a damaged file, and a file protected by a password, which pdf-lib does not decrypt. Remove the protection, sign, then protect the document again if you need to.

The line is jagged on my touchscreen

Drawing follows the browser’s pointer events, and finger accuracy on a capacitive screen stays limited. A stylus gets much closer to your real signature; failing that, draw large in the pad, since the crop brings the stroke back down to the size you asked for.

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