You can sign a PDF online for free by drawing your signature on a pad with a mouse, finger or stylus, or by uploading a saved signature image, then placing it on the page you choose. The file never leaves your device. This is a visual signature, not a certificate based digital signature.
The distinction matters more than the placement. A certificate based signature carries a cryptographic key, a timestamp and a way for a reader to check that the file has not changed, and a drawn signature carries none of those things. What this tool does is stamp a picture of your handwriting onto the page, which is what most everyday paperwork actually asks for. You control the page, one of nine positions, a width between 10% and 60% of the page width, and a fixed 5% margin. Near white pixels are stripped from the signature first, so no white box lands on top of the text.
The task sounds trivial until the form arrives with the signature line in an awkward place. A lease, a consent form or a supplier agreement turns up as a PDF, the person who needs to sign has no printer, and the file has to come back today. The usual workaround, print, sign, photograph, produces a picture of a page rather than a signed document. Adding the signature directly to the PDF keeps the text selectable, and doing it in the browser means the contract never reaches a stranger's server.
Sign PDF
Draw a signature or upload an image, then stamp it on the page and corner you pick. The PDF is opened and written in your browser and is never uploaded.
How to sign a PDF in three steps
Every run of the tool follows the same short path, and nothing is sent anywhere until you download the result.
- Add your PDF. Drop one file into the tool or click to browse. The page count is read on your device straight away, and the page field stops at the last page so an out of range number is refused before anything else happens. An encrypted PDF is reported here as unreadable rather than failing silently later.
- Draw or upload the signature. Sign on the white pad with a mouse, finger or stylus, or switch the source to Upload and pick a PNG or JPG. The pad can be cleared and redrawn as often as you need, and an uploaded image is trimmed of its empty border the moment it is added.
- Place it and download. Set the page number, choose one of nine positions and set the width between 10% and 60%. Click Sign PDF, check the output file name and size, then download the copy, which arrives as your original file name plus signed.
One PDF is signed per run, so a stack of forms is one pass each.
What the signed file is, and what it is not
What kind of signature ends up in the file matters more than where it goes. Three common approaches look similar on a screen and behave very differently.
| Method | What it puts in the file | Can a reader verify it | Audit trail |
|---|---|---|---|
| Aihangsoft drawn or uploaded signature | A picture of the signature placed on the page | No, the pixels are not tied to any identity | None |
| Certificate based digital signature | A cryptographic signature bound to a key and an identity | Yes, the reader reports the signer and any change | Usually, with a timestamp and a report |
| Print, sign by hand, scan | A photo or scan of the whole page as one image | No | None |
A certificate based signature, sometimes called an electronic signature in the strict sense, is built for the cases where someone has to prove later who signed and whether the file was altered. The drawn signature answers a different need: a document that requires your visible mark so it can be filed, forwarded or printed, where nobody is going to run a verification check.
If the paperwork says a certified or verified signature is required, this tool is not the right one, and no amount of careful drawing changes that. If the paperwork simply has a line marked Signature, a drawn or uploaded mark is exactly what it is asking for.
Where the signature lands on the page
Three settings decide where the signature lands.
Page and position
The page field takes any page number up to the length of your document, and the tool reads that count as soon as the file is added. Nine position presets sit on a three by three grid: the four corners, the four edge midpoints and the centre. Bottom right is the default because most forms carry a signature line near the bottom of the last page.
Width and margin
The width slider sets the signature as a share of the page width, from 10% to 60%, and the height follows the shape of your signature so nothing is stretched. The margin around the edge is fixed at 5% of the page width rather than being adjustable, which keeps the mark clear of the border and of anything a printer might not reach. If the signature would overrun the printable area at the width you chose, it is scaled down to fit before it is placed.
Drawing on the pad or uploading a saved signature
The signature source is a single switch, and the two options suit different habits.
Drawing with a mouse, finger or stylus
The pad handles pointer events, so a mouse, a touch screen and a stylus all draw the same way, and page scrolling is suppressed while you sign so the pad does not move under your hand. Ink is drawn in a fixed dark colour with a rounded, slightly thick line, which reads clearly at the small sizes a signature usually occupies. When you click Sign PDF the pad is read pixel by pixel, anything close to white is made fully transparent, and the border of empty space is trimmed away, so only the strokes reach the page.
Uploading a PNG or JPG
If you already have a signature saved, an image is faster and looks more consistent across documents. A PNG with a transparent background gives the cleanest result, and JPG works too, because the same rule is applied: any pixel where the red, green and blue channels are all at 240 or above becomes transparent, so a scan on white paper loses its surround instead of dropping a box onto the text.
What this tool does not do
These limits are deliberate, and knowing them saves a wasted attempt.
- It is not a certificate signature. The signature is an image on the page. It carries no key, no identity and no timestamp, so it cannot prove who signed the document.
- No PDF reader can verify it. Opening a signed file shows no signature panel entry and no validation result. Anyone with a PDF editor can move or delete the picture.
- There is no audit trail. Nothing records when the signature was added, from which device or by whom. If that record is required, use a certified signing service.
- It does not fill in form fields. Text boxes, checkboxes and signature fields in an interactive form are not typed into. The tool stamps a picture on the page, and interactive fields stay empty.
- An encrypted PDF has to be unlocked first. A password protected file cannot be read, so it is refused. Unlock it with the password you know, then sign the unprotected copy.
- One signature per run on one page. Signing two pages or two parties means running the tool twice, on the same file, with a different page or position each time.
Why the file never leaves your device
The reason to sign in the browser is not that server based tools are dishonest. A document you are signing is, by definition, one you did not want to expose: a lease with your address on it, an offer letter with a salary, a consent form with medical details. Uploading it to an unknown service leaves the file in plain form on a machine you do not control, along with the signature you just handed over.
Here the PDF is read from your own storage into the page, the signature is composited onto the chosen page, and the bytes are handed back as a download. There is no upload step, no account and no queue, and the signature image you draw or load is never transmitted, so there is nothing to delete later. The trade is that the work runs on your own machine, which is why a very large PDF can take a moment on an older device, and why closing the tab clears the session with no copy left anywhere.
When a certified signing service is the better choice
There are documents where a visible mark is not enough, and it is worth being blunt about them. Employment contracts with a legal review behind them, mortgage and loan paperwork, regulatory filings, and anything a counterparty's counsel has specified as requiring a verifiable signature all belong in a service that issues a certificate and a completion report. Those services charge for that assurance, and the fee buys the audit trail rather than the ink.
For the long middle of everyday paperwork, an internal approval, a timesheet, an equipment handover, a school trip consent form or a supplier's standard terms, a photographed signature is often all that is asked for, and a browser tool that costs nothing and keeps the file local does the job. If a recipient later asks for something verifiable, sign again with the service they name.