Electronic signatures vs digital signatures — what's the difference?
Before we get into how to sign a PDF, it's worth understanding the difference between two terms that are often confused:
Electronic signature — Any electronic indication of intent to sign a document. This includes a drawn signature image, a typed name, or an image of your handwritten signature pasted into the PDF. These are legally valid in most countries for most document types under laws like eIDAS (EU) and ESIGN (USA).
Digital signature — A cryptographic signature tied to a digital certificate that verifies the identity of the signer and detects any changes made to the document after signing. These are used in high-security contexts like banking, government, and legal contracts requiring identity verification.
For the vast majority of everyday documents — employment forms, rental agreements, consent forms, contractor agreements — an electronic signature is perfectly legal and sufficient. You don't need DocuSign or Adobe Sign for most of what you're signing.
Method 1: Sign using macOS Preview (Mac users)
Mac users can sign PDFs without any additional software using the built-in Preview app. Preview allows you to create a signature using your trackpad, camera, or iPhone — and then place it anywhere on the PDF.
Open the PDF in Preview
Right-click the PDF file → Open With → Preview.
Open the Markup toolbar
Click View → Show Markup Toolbar (or the pencil icon in the top right).
Click the Signature button
Click the signature icon (it looks like a cursive script). Choose Create Signature. You can draw it with your trackpad, take a photo of your written signature with your phone, or draw it with your finger on iPhone/iPad.
Place and save
Click on the signature you created. It will appear on the PDF. Drag it to the correct position, resize if needed, then save the file (Cmd+S).
Method 2: Sign using your browser (Chrome or Edge)
Modern browsers can open PDFs directly and, for PDFs with form fields, allow you to type into signature fields. For PDFs with a signature image field, you can sometimes upload an image of your signature directly.
Open the PDF by dragging it into your browser. If the form has interactive signature fields, click on them to type or insert your signature. Print to PDF to save. This works best for structured forms — not for placing a freehand signature on an arbitrary part of a document.
Method 3: Sign on iPhone or Android (no app needed)
On iPhone: Open the PDF using the Files app. Tap the pencil icon to open Markup. Tap the + button at the bottom right → Signature. Draw your signature with your finger, tap Done, then drag it to position. Tap Done to save.
On Android: Use Google Drive. Upload the PDF, open it, and if it contains form fields you can fill them in. For a drawn signature, use the Samsung Notes app (Samsung devices) or a third-party PDF app like Xodo, which is free and doesn't require an account.
Services like DocuSign, HelloSign, and Adobe Sign require you to create an account and upload your document to their servers. Your signed contract then lives permanently on their infrastructure. For sensitive documents — especially legal agreements, NDA forms, or financial contracts — consider whether you're comfortable with a third party storing your signed documents indefinitely. Always read the privacy policy of any e-signature service before use.
Method 4: Upload an image of your signature
The most flexible and universally compatible approach is to create a clean image of your signature and insert it into the PDF as an image. Here's how:
Sign your name on plain white paper with a black pen. Take a photo with good lighting (or scan it). Crop the image tightly around your signature. For best results, use an image editing tool to make the background transparent (PNG format). Then use the Watermark PDF tool or a PDF form filler to insert the signature image in the right location on the PDF.
This method gives you a signature that looks exactly like your real handwritten signature on any PDF.
Is an electronic PDF signature legally valid?
In most countries, yes. Electronic signatures have the same legal standing as handwritten signatures for the majority of documents under these key laws:
In the USA, the ESIGN Act (2000) and UETA give electronic signatures full legal validity for most commercial transactions. In the European Union, the eIDAS regulation establishes three tiers of electronic signatures, with the basic tier (which includes drawn and typed signatures) legally valid for most business documents. In the UK, the Electronic Communications Act 2000 and eIDAS-derived regulations provide similar protection. In Australia, the Electronic Transactions Act covers e-signatures federally.
Exceptions exist for certain documents: wills, some court documents, notarised documents, and real estate transfers in some jurisdictions may require wet (physical) signatures or higher-assurance digital certificates. When in doubt about a specific document type, consult a legal professional.
How to keep a record of signed documents
Once you've signed a PDF, keep a copy in a safe location. Good practices include saving a copy to a local hard drive or encrypted backup, emailing yourself a copy as an attachment for a searchable email record, storing in a cloud folder (Google Drive, Dropbox, iCloud) specifically for signed legal documents, and keeping the original unsigned version as well for reference.
If the document is particularly important — an employment contract, property agreement, or business contract — consider printing and physically signing an additional copy to keep in a secure location alongside the digital version.
Create a high-resolution transparent PNG of your signature once (white background → remove background using a free tool like remove.bg). Save it to your phone and computer. Whenever you need to sign a PDF, you can insert this signature image quickly without redrawing it each time.
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