How to Sign a PDF: E-Signature vs Digital Signature

The short answer

To sign a PDF, open it in a signing tool, make your signature by drawing it, typing your name or uploading a photo of it, drop it on the signature line, and save a new copy. Sign PDF does this in your browser, so neither the document nor your signature is uploaded.

For most everyday US paperwork, such as a lease, an offer letter, a permission slip or an invoice, that kind of signature is legally fine. Federal law says a signature can’t be denied legal effect just because it’s electronic. But there are documents the law carves out, and the person asking for your signature can insist on something else. The rest of this guide covers both, plus the difference between an e-signature and a certificate-based “digital signature”, which people mix up all the time.

Two different things called “signing a PDF”

	Visual electronic signature	Certificate-based digital signature
What’s added to the PDF	An image of your signature, or your name in a script font, on the page	A cryptographic signature over the file, made with a key tied to a certificate
Proves who signed	No, only that someone placed it	Yes, through whoever issued the certificate
Shows later changes	No	Yes, the signature reads as invalid if the file changes
Needs an account or certificate	No	Yes
Typical use	Leases, HR forms, school forms, invoices	Some government, court, banking and corporate workflows

NIST’s Digital Signature Standard (FIPS 186-5) sums up the second kind: digital signatures “are used to detect unauthorized modifications to data and to authenticate the identity of the signatory.” A drawn or typed signature on a page does neither. It is the on-screen version of signing a printout and scanning it back.

Our tool makes the first kind only. If a bank, court or government portal asks specifically for a “digital signature” or a certificate, use the service it names.

What US law says

Two laws do most of the work, and they say much the same thing.

The federal ESIGN Act (2000). For transactions in or affecting interstate commerce, 15 U.S.C. § 7001(a) says a signature, contract or other record “may not be denied legal effect, validity, or enforceability solely because it is in electronic form.” The Act defines an electronic signature broadly: “an electronic sound, symbol, or process” attached to or logically associated with a record and “executed or adopted by a person with the intent to sign the record.” A drawn signature, a typed name or a scanned image can all qualify. The key word is intent.

The Uniform Electronic Transactions Act (UETA). A model law written in 1999 by the national body of state law commissioners (now the Uniform Law Commission) for states to adopt. Section 7 says a record or signature may not be denied legal effect or enforceability “solely because it is in electronic form,” and that if a law requires a signature, an electronic signature satisfies it.

Two limits are built into both laws, and they matter more than the rule itself:

• Both sides have to agree to go electronic. UETA section 5 says the Act applies only between parties that have each agreed to conduct the transaction electronically, judged from the context and their conduct. ESIGN § 7001(b) says nobody is required to agree to use or accept electronic signatures. So a landlord or employer can ask for ink, and you can ask to sign on paper.
• Some documents are excluded. ESIGN’s general rule does not apply to the categories listed below.

When an e-signature isn’t enough

ESIGN § 7003 lists the exceptions:

• Wills, codicils and testamentary trusts.
• Adoption, divorce and other family-law matters governed by state law.
• Court orders, notices and official court documents required in court proceedings.
• Certain notices to consumers: cancellation of utility service (water, heat, power); default, repossession, foreclosure or eviction involving your primary residence; cancellation of health or life insurance benefits; and product recalls that risk health or safety.
• Documents that must travel with hazardous materials, pesticides or other dangerous materials.
• Most of the Uniform Commercial Code, apart from sales and leases of goods (Articles 2 and 2A) and two other sections.

Beyond those, the person or office you’re dealing with sets the rules. Anything that must be notarized, many government forms, and documents a bank or court specifies follow their own requirements, which may mean ink, an in-person signature, or a particular e-signing service. When in doubt, ask the recipient what they accept before you sign.

Step by step: sign a PDF in your browser

1. Open Sign PDF and drop in the document. Pages are shown one at a time.
2. Make your signature in one of three ways:
   • Draw with a finger, stylus or mouse. Sign big; it’s scaled down when placed.
   • Type your name; it’s set in a handwriting-style font. This is the way to sign without a mouse or touchscreen.
   • Upload a photo of your signature on white paper. A “Paper removal” slider turns the paper transparent; lower it if grey paper remains, raise it if thin strokes vanish.
3. Pick ink and size. Black or blue. Small fits up to 1.6 inches wide, Medium 2.25 inches and Large 3 inches. A typical signature line is 2 to 3 inches, so Medium suits most forms.
4. Go to the right page and press Place signature. Drag it onto the line and resize it. Arrow keys nudge a selected item by one point (Shift moves ten).
5. Add initials and the date if the form asks. Today’s date comes from your device’s clock in the format you choose (MM/DD/YYYY, Month D, YYYY, DD/MM/YYYY or YYYY-MM-DD). “Add text” covers anything else, like a printed name.
6. Repeat on other pages. The same signature is reused each time you press Place signature; Duplicate copies an item on the same page.
7. Save signed PDF. A new copy downloads and your original is unchanged.

Getting a signature that looks like yours

A mouse signature rarely does. A finger on a phone screen, or a stylus on a tablet, looks much more natural. For the photo route, use a black or dark blue pen on plain white paper, sign larger than usual, and shoot straight down in daylight without your shadow on the page.

Privacy: who sees your signature

The tool draws and saves everything inside the browser tab. Nothing is sent to a server or stored after you close the tab. But the signed PDF contains your signature as an image, so anyone who receives the file could copy it, exactly as they could from a scanned signature. Send signed documents only to the people who need them.

Common problems

• “This PDF cannot be changed.” The file is encrypted, either needing a password or locked against editing, which is common with bank and e-signing service files. If you’re allowed to sign it, open it, choose Print, then “Save as PDF” (or “Microsoft Print to PDF”), and sign the printed copy.
• The recipient wanted a digital signature. A visual signature won’t satisfy that request. Use the platform or certificate they specify.
• The document already has a certificate signature. Adding anything changes the file, and certificate signatures are designed to detect changes. Ask whether you should sign through the original service instead.
• Fillable form, sign afterwards. Fill in the fields first. The tool leaves the rest of the document, including form fields, as it was and draws your signature into the page.

Before you send it

1. Is this one of the excluded documents, or does it need a notary? If so, don’t rely on an e-signature.
2. Did the recipient agree to electronic signing, and does it accept this kind?
3. Is every signature, initial and date in the right place? Zoom to 100% and check.
4. Are you sending it only to the people who need it?

For everything else, Sign PDF lets you sign, initial and date a document on your own device in a couple of minutes.

This guide is general information about US law, not legal advice. For a specific document or situation, check with the recipient or a lawyer.