The document nobody made a form out of
Almost every PDF you get asked to sign or fill in was never built as a form. It is a scan, or an export from Word, or something that has been printed and photographed. There are no fields to click into, which is why the usual advice is to print it, write on it, and scan it back.
So this does not care whether the document has fields. You put a box wherever it needs to go and put something in it, exactly as you would with a pen.
Everything is a box you drag
A signature box is one you draw inside. A text box is one you type in. A tick is a small one. Drag any of them by the coloured bar at the top, or select one and nudge it with the arrow keys, which is more precise than a mouse and works without one.
What you see on the page is where it lands. The position is stored as a proportion of the page rather than as screen pixels, so it is the same whatever size your window is and whatever screen you are on.
How this tool works
Every page is drawn once so you can see what you are signing, and everything you add is a box you can drag around on top of it. Positions are held as a fraction of the pagerather than as screen pixels, so the preview can be any size and the browser can be resized halfway through and the number handed to the PDF is still right.
Your signature is stored as the strokes you drew, not as a picture of the screen, and it is redrawn at roughly print resolution when it goes into the document. That is why it stays sharp even though you drew it in a small box on a phone.
Draw the signature, do not type it
You can sign with a finger on a phone or a tablet, or with a mouse. A finger is considerably better than a mouse and a stylus is better again.
The drawing is captured as strokes rather than as a picture of the screen, then redrawn at roughly 300 dots per inch when it goes into the PDF. So a signature drawn in a small box on a laptop still comes out sharp when the document is printed, which is not true of tools that simply screenshot the preview.
It is flattened, deliberately
The signature and any text are drawn into the page content itself, not added as annotations.
That matters. An annotation is a separate object sitting on top of the page, and anybody who opens the file can drag it somewhere else, edit it or delete it. A signature that a recipient can move is not a signature. There is deliberately no "keep it editable" option here, because the point of signing something is that it stops being editable.
Is it legally valid
For most everyday agreements in the UK, yes. Electronic signatures are recognised under the Electronic Communications Act 2000 and the retained eIDAS regulation, and the Law Commission confirmed in 2019 that a simple electronic signature is capable of executing most contracts, including where a document says it must be signed.
The exceptions worth knowing: deeds need a witness who actually watched you sign, wills have their own strict rules, and some land registrydocuments require a specific form of signature. Employment contracts, quotes, purchase orders, subcontractor agreements, delivery notes and the usual run of site paperwork are all fine.
None of that is legal advice. If a document matters enough to worry about, it matters enough to ask somebody qualified.
What this does not do
It does not add a cryptographic digital signature, the sort that carries a certificate and shows a green tick in Adobe Reader. That needs a certificate issued by a trust service provider, which means an account, an identity check and usually a fee, and none of those can happen on a page that asks nothing of you.
What you get here is the electronic equivalent of signing with a pen, which is what nearly every document actually needs, and it is what the vast majority of "e-signature" services are really providing behind a subscription.
Your signature is the piece of you worth most to a stranger
The pages are drawn and the signed document is built on this page, using your own machine. Your signature never touches a server, which is worth more here than anywhere else on this site: it is the one piece of you that a company would most like to keep on file.
Common questions
How do I sign a PDF for free without an account?
Drop the PDF in, add a signature box, draw your signature straight into it with a mouse or a finger, drag it where it goes and apply. No account, no email, no watermark, and nothing is uploaded.
Can I fill in a PDF that has no form fields?
Yes, and that is the usual case. Most PDFs people are asked to fill in are just scans or exports with no fields at all. Text boxes here sit anywhere on the page, so it does not matter whether the document was built as a form.
Is a signature drawn like this legally valid in the UK?
For most everyday agreements, yes. UK law recognises electronic signatures under the Electronic Communications Act 2000 and the 2016 eIDAS regulation, and the Law Commission confirmed in 2019 that a simple electronic signature can execute most contracts. Deeds, wills and some property documents have extra requirements. If it matters, take advice.
Can someone move or delete my signature afterwards?
No. It is drawn into the page itself rather than added as an annotation. Annotations can be dragged off or deleted by anyone who opens the file, which is not much of a signature. This is flattened into the page content.
Is my document uploaded to sign it?
No. The pages are drawn and the signed PDF is built on this page using your own machine. You can confirm it in your browser network tab. There is no page limit, no watermark and no account.