Sign a PDF

How to use it

1. 1

   Open the document

   Every page renders as a thumbnail beside the viewer, so a signature block on page nine is one tap away.

2. 2

   Make your signature once

   Draw it with a finger, a stylus or a mouse in black, blue or red; type it in one of four hands; or photograph a wet signature and let the paper behind it be removed.

3. 3

   Choose what a tap adds

   Signature, initials, the date, or any text you type. Initials come from the name you typed, so they match the hand your signature is in.

4. 4

   Tap the page where it goes

   The mark lands centred on that point. Drag it to move, pull the corner handle to resize, use the arrow keys to nudge, and put it on every page in one press if the document needs initialling throughout.

5. 5

   Sign and download

   Every mark is drawn into a new copy of the file in this page. The original is untouched.

A drawn signature and a digital signature are different things

What this makes is an image of your handwriting placed on a page. A certificate based digital signature is something else: a cryptographic hash over an exact byte range of the file, bound to a certificate issued to a named person, which shows immediately whether a single byte has changed since. The European PAdES profiles go further again, embedding the certificate chain, revocation data and a trusted timestamp so the signature still verifies decades later. One is a picture. The other is evidence.

When a drawn signature is enough

Under the US ESIGN Act a signature cannot be denied legal effect purely because it is electronic, and UETA says much the same in the states that adopted it. Under eIDAS a drawn mark is a simple electronic signature: valid, but the weakest of the three tiers, and easier to dispute than an advanced or qualified one. In practice it covers internal approvals, delivery notes, school forms and most of what you would otherwise print, sign and scan. It stops being enough when a bank, a regulator or a counterparty has told you which standard they require.

Your signature stays on your device, if you want it kept at all

Signatures you make are held in memory for the session so you can reuse them across pages without redrawing. Remembering them between visits is off by default and lives under Advanced options, because a signature image is the kind of thing you do not want left behind on a shared computer. Turn it on and the image is written to this browser's local storage only. Turn it off and it is deleted. Either way it is never sent anywhere.

Points, not pixels

PDF pages are measured in points, at seventy two to the inch, so an A4 page is 595 by 842 points however it is displayed. Signature width is set in points for that reason: 160 points is about 5.6 centimetres, roughly a handwritten signature on paper. Setting it in points means the mark comes out the same physical size on a phone screen and on a printed sheet, and pages carrying a rotation flag are handled so a landscape page gets its signature the right way up.