How to sign a PDF with an electronic signature

What does it mean to sign a PDF electronically?

When people say they want to e-sign a PDF, they almost always mean placing an image of their signature on the page, saving the file and sending it back. US law calls this an electronic signature, and it is valid for most agreements. A separate thing, the certified digital signature, uses a cryptographic certificate to prove who signed and whether the file changed afterwards. Most everyday paperwork needs the first kind.

Every method below produces the first kind: a visible signature embedded in the PDF.

How to sign a PDF online for free

Sign PDF works in any browser on a phone or computer. It is free, does not ask you to create an account, adds no watermark, accepts files up to 300 MB, processes them in memory on DocGopher's own servers and deletes them after 30 minutes.

If the document also needs today's date or your printed name on a line, add them with Edit PDF before or after signing.

1. Open Sign PDF and drop your PDF onto the page, or tap to pick it from your phone.
2. Create your signature: draw it with your finger, trackpad or mouse, type your name and pick a handwriting style, or upload a picture of your signature.
3. Click or tap the spot on the page where the signature belongs. Drag the corners to resize it and move it until it sits on the line.
4. To sign in more than one place, click Add another spot and drag the copy where it goes; each spot has its own x to remove it. For a contract that must be initialed on every page, tick Put it on every page.
5. Download the signed PDF. Open it to check the placement, then send it.

How to sign a PDF on a Mac with Preview

Preview, which comes with every Mac, has a signature tool and remembers your signature for next time.

Preview also has a Text tool for the date. The result is a visual signature, like the browser method.

1. Open the PDF in Preview and click the Markup toolbar button (the pen tip in a circle), or press Shift-Command-A.
2. Click the Sign button. Choose Trackpad to draw with your finger, Camera to hold a signature on white paper up to the webcam, or iPhone to draw on your phone's screen.
3. Click Done. Your signature now appears in the Sign menu; click it to drop it onto the page.
4. Drag the signature into place and resize it with the corner handles. Repeat for each spot that needs it.
5. Choose File, then Export, to save a copy.

How to sign a PDF on an iPhone or iPad

iOS has signing built in through Markup, in both Files and Mail.

On Android, the free Adobe Acrobat Reader app has Fill & Sign, and the browser method works on any Android phone.

1. Open the PDF in Files, or tap the attachment in Mail.
2. Tap the Markup pen icon (a pen tip in a circle), then the plus button in the lower right, then Signature.
3. Draw your signature with your finger, tap Done, and it appears on the page. Drag it into place and pinch to resize.
4. Tap the plus button again and Text to add a date. Tap Done when finished.
5. In Files, the change is saved in place. In Mail, tap Done and choose Reply All to send the signed copy back.

How to sign a PDF on Windows

Windows has no signature tool of its own, but two free programs you probably already have cover it, and the browser method above works too.

• Microsoft Edge: open the PDF in Edge, click Draw in the toolbar, pick a pen color, and sign with the mouse, a touchscreen or a stylus. Save with the save icon. Signing neatly with a mouse takes practice; a touchscreen or a typed signature is easier.
• Adobe Acrobat Reader (free): open the PDF, choose Fill & Sign, click Sign yourself, then Add signature. Type, draw or upload an image, click Apply and place it on the page. Acrobat Reader also saves your signature for reuse.
• Any browser: Sign PDF from DocGopher works in Chrome and Edge on Windows with nothing to install.

How to get a clean signature image from paper

If you want your real handwritten signature rather than a drawn or typed one, make a reusable image once.

Keep the file private: a clean signature image is exactly what a forger needs.

1. Sign your name with a black or dark blue pen on plain white paper, larger than usual.
2. Photograph it in good light, straight on, or scan it, then crop to the signature.
3. Remove the paper background with Make background transparent so the signature can sit over text and lines without a white box around it. Save it as a PNG.
4. Upload that PNG in Sign PDF whenever you need it.

Visual signature vs certified digital signature: what is the difference?

The signature that all of the methods above produce is visual. It is a picture or vector drawing of your signature placed on the page, sometimes with your name and the date. It shows intent, which is what the law asks for in most cases. It does not prove the document was unchanged after signing, and anyone can copy the image onto another file.

A certified digital signature, also called a digital signature, is different. The signer holds a digital certificate issued to them, and the PDF stores a cryptographic hash of the document signed with that certificate. A viewer such as Acrobat Reader shows a panel stating who signed, when, and whether the document has been modified since. Changing even a comma breaks the seal. Government filings and some regulated industries require this kind.

DocGopher's Sign PDF creates a visual signature only, as do Preview, iPhone Markup and Edge. For a certified digital signature you need a certificate (from your employer or a certificate authority) and a tool that supports it, such as Adobe Acrobat, or a paid e-signature service that adds an audit trail and a tamper seal to the signed copy.

Is an electronic signature legally valid in the US?

Yes, in most situations. The federal ESIGN Act of 2000 and the Uniform Electronic Transactions Act (UETA), which nearly every state has adopted, give an electronic signature the same legal standing as ink. Under these laws an electronic signature is any electronic sound, symbol or process attached to a record with the intent to sign. A signature image on a PDF qualifies, and so does a typed name.

What makes a signed PDF hold up is less the technology than the surrounding facts: that you meant to sign, that the other party agreed to do business electronically, that the signature is attached to the document, and that both sides keep a copy. Keeping the email thread in which you sent the signed PDF covers most of this.

A visual signature is enough for most everyday paperwork: leases and rental applications, offer letters, NDAs, contractor and freelance agreements, consent and permission forms, most school and medical intake forms, invoices, quotes, purchase orders, timesheets, and internal approvals and HR paperwork.

It is not enough, or the law excludes it, in the cases below. When in doubt, ask the recipient before you sign.

• Wills, codicils and testamentary trusts, which the ESIGN Act excludes.
• Adoption, divorce and other family law documents, and court orders and official court filings.
• Notices of foreclosure, eviction, repossession or default on a primary residence, and notices canceling utility service or health or life insurance.
• Documents that must be notarized or witnessed, such as deeds and many powers of attorney, unless your state allows remote online notarization.
• Anything where the recipient specifies a certified digital signature, a particular e-signature platform or a wet-ink original.

After you sign: protect and send the file

A signed PDF is still an ordinary PDF, and anyone with an editor can copy the signature image. Three habits reduce the risk.

• Lock it: Protect PDF adds a password with AES-256 encryption, so the file opens only for people who know it. Share the password by a different channel.
• Keep it small: if the signature image came from a photo, the file may have grown. Compress PDF brings it back down for email attachments.
• Keep your copy: save the signed version and the email in which you sent it. Under the ESIGN Act, a record that can be retained and accurately reproduced is part of what makes the signature enforceable.