How to sign a PDF online for free

Someone emails you a PDF and asks you to “sign and send it back”. You could print it, sign it with a pen, scan it and email it. Or you can add your signature directly to the PDF in a couple of minutes, without a printer and without creating an account.

This guide shows how to do that with a free tool that runs in your browser, and explains plainly what kind of signature you end up with, because that matters for some documents.

How to sign a PDF

Open Sign PDF and add the document. The PDF stays on your device; it’s not uploaded.

1. Create your signature

You have three ways to make it:

• Draw it with your mouse, trackpad or finger. On a phone or tablet, drawing with a finger often looks the most natural.
• Type it. Enter your name and choose from a few handwriting-style fonts.
• Upload a photo of it. Sign a sheet of white paper, take a close-up photo in good light, and upload it. The tool removes the paper background so only the ink is placed on the page.

2. Place it on the page

The document opens on its last page, where signatures usually go. From there:

• Drag the signature to the right spot, such as the signature line.
• Resize it by dragging its corner. The signature keeps its shape as you resize.
• Use the arrows to move between pages.
• Click Add to this page to place the signature on more pages, for example to initial each page. Remove from this page takes it off again.

3. Download

Click Sign PDF. You’ll get a new copy of the document with “-signed” added to the file name. Your original file isn’t changed.

Getting a clean signature image

If you upload a photo, the cleaner the photo, the better the result:

• Use a dark pen (black or blue) on plain white paper.
• Photograph it close up, with the phone parallel to the paper.
• Use daylight or bright, even light, and avoid your phone’s shadow.

If you need a signature image for other uses too, such as an upload form or a document template, the signature resizer turns a photo into a clean, cropped image. It removes paper texture and shadows, can make the ink black or blue, and can save a transparent PNG you can place on documents.

What this tool doesn’t do

To be clear about its scope, Sign PDF places an image of your signature on the pages you choose. It doesn’t:

• fill in form fields or add text boxes (like your printed name or the date),
• send the document to other people to sign, or track who signed when,
• add a certificate-based digital signature.

If the PDF is password-protected, unlock it first with Unlock PDF (you’ll need the password).

Is a picture signature legally valid?

This is the question most people have, so here’s the general picture. It’s plain information, not legal advice, and the rules depend on your country, the type of document and what the other party agrees to.

Electronic signature vs. digital signature

The two terms sound alike but mean different things:

• An electronic signature is a broad term for any electronic sign that someone agreed to something. A typed name, a click on “I agree”, and a picture of your handwritten signature placed on a PDF can all count.
• A digital signature (sometimes called a certificate-based signature) uses cryptography. It’s tied to a verified certificate, and PDF readers can check whether the document was changed after it was signed.

Sign PDF creates the first kind. It’s like signing a printout and scanning it back in: it shows your signature and your intent, but it doesn’t carry a certificate, an audit trail or tamper protection.

What the law generally says

Many countries accept electronic signatures for a wide range of everyday documents:

• In the United States, the federal ESIGN Act and the Uniform Electronic Transactions Act (UETA), adopted by most states, generally say a signature can’t be denied legal effect just because it’s electronic. There are exceptions, such as wills and certain family-law and court documents.
• In the European Union, the eIDAS regulation recognizes three levels: simple, advanced and qualified electronic signatures. A picture signature is a simple electronic signature. Only a qualified electronic signature automatically has the same legal effect as a handwritten one across the EU, though simple signatures can’t be rejected as evidence purely for being electronic.
• Other countries have their own laws, often with similar ideas and their own lists of exceptions.

When a picture signature is usually fine

For many everyday documents a signed PDF is commonly accepted: a rental application, a school or club form, a freelance agreement, an internal company form, or a letter of authorization. The other party just needs a signed copy and is happy with this method.

When you may need something stronger

Some documents typically need more than a picture signature:

• documents that must be notarized or witnessed,
• wills and many property, family-law or court documents,
• some government, banking and loan documents,
• any case where the other party specifically asks for a certified digital signature or a particular signing service.

When in doubt, ask the person or organization requesting the signature what they accept. For anything with serious legal or financial consequences, check with a qualified professional where you live.

A note on PDFs that are already digitally signed

If a PDF already contains a certificate-based digital signature (for example, one signed by the other party through a signing service), changing the file afterwards, including adding a signature image, will usually make that existing signature show as invalid or modified when someone checks it. In that case, ask the sender how they want you to sign.

Sending the signed PDF

• Check it first. Open the signed copy and make sure your signature is on every page it should be, in the right place.
• Complete other fields separately. Sign PDF only adds signatures, so if there are fields to fill in, ask the sender for a fillable version or use a PDF app that supports forms.
• Protect it if it’s sensitive. Protect PDF adds a password with AES-256 encryption. Share the password separately from the file, for example by text message.
• Keep your copy. Store the signed version alongside the original.

Why sign in the browser?

Your signature is personal. With Sign PDF, both the document and your signature are processed on your own device, and nothing is uploaded to Treeet. You don’t need an account, and it works on phones as well as computers.