Is a signature from an online signature generator legally valid?

It can be. Under the US ESIGN Act, an electronic signature is any electronic sound, symbol or process you adopt with the intent to sign. A generated image counts when you use it that way, though on its own it doesn't prove who placed it or that the document wasn't changed.

What's the difference between creating an electronic signature and a digital signature?

An electronic signature is a mark you adopt to sign, like a drawn or typed name. A digital signature is a cryptographic value made with a private key and tied to a certificate, and it shows whether a file changed after signing.

Can I create a digital signature for free?

You can make a self-signed certificate yourself, for example with Microsoft's SelfCert tool for Office. Microsoft notes that other people can't verify it unless they manually choose to trust it, so it's mostly useful for testing or internal use.

What file format should I save my signature image in?

PNG is the usual choice because it can have a transparent background, so the signature sits cleanly on the line instead of inside a white box. Word and most PDF apps accept PNG and JPG.

How to Create an Electronic Signature (and When You Need More)

You create an electronic signature by drawing your name with a finger, mouse or stylus, typing it in a script font, or taking a photo of your real signature and cropping it. Any of those can be a legal signature in the US if you use it with the intent to sign. A digital signature is something else: a cryptographic seal that needs a certificate, and you only need one in specific situations.

Most people searching for this want the first thing, a clean image of their signature they can drop into PDFs and Word files. So let’s start there.

What counts as an electronic signature?

Under US federal law, an electronic signature is “an electronic sound, symbol, or process, attached to or logically associated with a contract or other record and executed or adopted by a person with the intent to sign the record.” That’s the definition in the ESIGN Act, 15 U.S.C. § 7006.

So it doesn’t have to look like your handwriting, and it doesn’t need any special software. What makes something a signature is that you adopted it to sign that document. A squiggle drawn on a phone qualifies. So can a typed name. If you want to see how the rest of that law works, we walk through it section by section in the ESIGN Act explained.

What are the ways to create an electronic signature?

There are three common ways: draw it, type it, or use an image of your handwritten signature. Each has trade-offs.

Drawing your signature

Drawing means signing on a screen with a finger, stylus, trackpad or mouse. It’s the closest to signing on paper, and it’s the default in most signing tools. The quality depends entirely on the hardware. A stylus on a tablet gives you something that looks like your real signature. A laptop trackpad usually gives you a shakier, blockier version.

Typing your signature

Typing means entering your name and letting the tool render it in a handwriting-style font. It’s fast, consistent and readable. It won’t look like your actual signature, and that’s fine for most everyday paperwork. Some people find it feels too casual for bigger agreements, which is a matter of taste more than law.

Using an image of your handwritten signature

This is the option most people end up keeping. Sign a sheet of plain white paper with a dark pen (a felt-tip or gel pen tends to show up better than a light ballpoint), then scan it or photograph it in good, even light. Crop tight around the signature and save it.

Save it as a PNG if you can, and remove the white background so it’s transparent. That way it sits on the signature line naturally instead of covering the line with a white rectangle. Keep the file somewhere private. Anyone who has the image can paste it anywhere.

How do I use an online signature generator?

An online signature generator lets you draw or type your signature on a web page and download it as an image, usually a PNG. It’s the easiest way to get a clean signature file if you don’t want to fiddle with scanning and cropping.

What to check before using one:

Does it upload your signature? Some generators process everything in your browser. Others send what you draw to a server. For something as personal as your signature, the in-browser kind is the better choice. The site should say which it does.
Is it actually free? A few “free” generators only reveal the download button after you create an account or start a trial.
Can you get a transparent PNG? That’s the format you’ll want for dropping into documents.

Keep in mind that what you download is just an image. It’s a perfectly good way to create an electronic signature, but on its own it proves nothing about who placed it on a document or whether the document changed afterward.

Where can I create a signature in apps I already have?

You can create and store a signature in several tools you probably already use, and they’ll remember it for next time.

Adobe Acrobat Reader (free): in Fill & Sign, choose Add your signature or initials, then type, draw, or add an image. Adobe’s page also mentions a camera icon for taking a new photo of your signature.
Preview on a Mac: click the Sign button in the Markup toolbar and create a signature with the trackpad, the built-in camera (hold your signature on white paper up to it), or a nearby iPhone or iPad. Apple says signatures sync to your other Macs if you use iCloud Drive.
Microsoft Word: insert a picture of your signature, or draw one on the Draw tab. Details in how to insert a signature in Word.

How do I create a digital signature?

To create a digital signature, you need a digital certificate and software that signs with the private key linked to it. The signing happens in software, as math applied to the whole file, so there’s nothing to draw.

NIST’s Digital Signature Standard (FIPS 186-5, published February 3, 2023) explains the purpose: digital signatures “are used to detect unauthorized modifications to data and to authenticate the identity of the signatory.” It also notes they can serve as evidence to a third party that the signature was really made by the claimed signer, which it calls non-repudiation.

For the certificate, you have two broad paths. Microsoft’s Office guide says certificates are “typically issued by a certificate authority (CA),” and that you can buy one or, from some providers, get one free. Employers and government bodies sometimes issue their own. Or you can make a self-signed certificate, for example with Microsoft’s SelfCert tool for Office. Microsoft is upfront about the limitation: if you share a document signed that way, “other people cannot verify the authenticity of your digital signature without manually deciding to trust your self-signed certificate.”

Once you have one, Word can add it through a signature line or an invisible signature under File > Info > Protect Document > Add a Digital Signature, and Microsoft says the signed file becomes read-only. The deeper comparison is in electronic signature vs digital signature.

Which one do you actually need?

For most everyday paperwork, a drawn, typed or image signature is all you need, and you don’t need to buy a certificate. You’d look at a certificate-based digital signature when a government portal, a regulator, a counterparty or a contract specifically asks for one.

Imagine Leo, a freelance web developer, signs a $6,000 project agreement by pasting his PNG signature into the client’s PDF and emailing it back. Legally, that’s probably fine. But if the client later edits the payment terms and sends back “the signed version,” there’s nothing in the file that shows it changed. A signing service that seals the finished PDF with a digital signature fixes exactly that, without Leo ever buying a certificate himself.

If you just want a clean signature image to start with, SignWren has a free signature generator that runs in your browser and doesn’t upload anything. And when you’re ready to send documents out for signature with a sealed PDF and audit trail, join the waitlist for early access.