How to Add a Signature to a PDF (Every Method, Every Device)

Signing a PDF Doesn't Have to Be Complicated

Whether you're finalizing a freelance contract, signing a rental agreement, or approving a school permission form, knowing how to add a signature to a PDF is one of those skills that saves you real time. No printing, no scanning, no hunting for a fax machine.

The good news: there are several ways to do it — on Windows, Mac, iPhone, Android, or directly in your browser — and most of them are completely free. This guide walks you through every practical method so you can pick the one that works best for your situation.

What Counts as a Valid PDF Signature?

Before diving into the how-to, it helps to understand the two main types of PDF signatures:

• Electronic signatures — A digital image of your handwritten signature, a typed name, or a drawn signature inserted into the document. These are legally valid for most everyday purposes (contracts, consent forms, business agreements) in the US, UK, EU, and many other countries.
• Digital signatures — A cryptographically secured signature tied to a certificate authority. These are used in highly regulated industries like banking, healthcare, and government and require special software or a third-party certificate provider.

For the vast majority of people reading this, an electronic signature is exactly what you need. That's what we'll focus on here.

How to Add a Signature to a PDF on Desktop

On a Mac (Using Preview — No Extra Software Needed)

Mac users have it easy. The built-in Preview app lets you insert a signature in a PDF in under a minute:

1. Open your PDF in Preview.
2. Click the Markup Toolbar icon (the pencil tip icon near the top right).
3. Click the Signature button (it looks like a cursive signature).
4. Choose Create Signature and either draw it with your trackpad, type it, or hold a signed piece of paper up to your camera so Preview captures it.
5. Click Done, then click your saved signature to insert it into the document.
6. Drag and resize it to position it correctly, then save the file.

Preview stores your signature for future use, so you only have to create it once.

On Windows (Using Adobe Acrobat Reader — Free Version)

Windows doesn't have a built-in PDF signing tool as slick as Preview, but Adobe Acrobat Reader (the free version) handles it well:

1. Open your PDF in Adobe Acrobat Reader.
2. Click Fill & Sign in the right-hand panel (or go to Tools > Fill & Sign).
3. Click the Sign icon in the toolbar and select Add Signature.
4. Choose to type, draw, or upload an image of your signature.
5. Click Apply and place the signature where needed on the document.
6. Save the file.

Using a PDF Editor Tool Online

Don't want to download software? An online PDF editor is often the fastest option — especially if you're on a shared computer or just need to sign something quickly. WriteGenius's PDF Editor lets you open a PDF in your browser, drop in your signature, and save the finished document without installing anything. It's a clean, no-fuss solution whether you're on Windows, Mac, or Linux.

How to Insert a Signature in a PDF on Mobile

On iPhone or iPad

iOS makes this surprisingly seamless with the built-in Markup feature:

1. Open the PDF in the Files app or Mail.
2. Tap the pencil icon to open Markup.
3. Tap the + button at the bottom right and select Signature.
4. Draw your signature with your finger (or an Apple Pencil), then tap Done.
5. Drag the signature to the correct spot and resize as needed.
6. Tap Done again to save.

On Android

Android doesn't have a universal built-in signing tool, but you have two solid options:

• Adobe Acrobat for Android (free) — Open the PDF, tap the pencil icon, choose Fill & Sign, and draw or type your signature.
• Google Drive — Open the PDF in Google Drive, tap the pencil icon, and use the annotation tools to draw your signature directly on the document.

How to Put a Signature on a PDF Using a Typed or Image-Based Signature

Not everyone wants to draw their signature with a mouse or finger — and that's completely fine. Here are two popular alternatives:

• Type your name — Most PDF signing tools let you type your name and choose a script-style font that resembles a handwritten signature. It's legally valid in most cases and looks clean and professional.
• Upload a signature image — Sign your name on white paper with a black pen, take a clear photo or scan it, and save it as a PNG file (with a transparent background if possible). Then upload this image into any PDF editor and position it on the signature line.

Pro tip: When creating a signature image, use a free background remover tool to eliminate the white background. This makes it look like you signed directly on the document rather than pasting a white box over the text.

How to Add a Signature to a PDF in Google Docs or Google Drive

If you're working with PDFs through Google Drive, here's a quick method:

1. Right-click your PDF in Google Drive and open it with Google Docs. (Note: This converts it to a Docs file.)
2. Go to Insert > Drawing > New.
3. Use the Scribble tool to draw your signature.
4. Click Save and Close to insert it into the document.
5. Download the file back as a PDF via File > Download > PDF.

This method is a bit roundabout but works well if you're already living in Google's ecosystem.

How to Remove a Signature from a PDF

Sometimes you need to go the other direction — whether you signed the wrong document, placed your signature in the wrong spot, or received a PDF you need to edit before re-signing.

Here's how to handle it depending on the situation:

• If you haven't saved yet — Simply undo the action (Ctrl+Z on Windows, Cmd+Z on Mac) to remove the signature before saving.
• If the PDF was saved with the signature as an annotation — Open the file in Adobe Acrobat Reader or Preview, right-click the signature, and select Delete.
• If the signature is a certified/locked digital signature — These are intentionally difficult to remove. You may need the original signer to revoke it, or you'll need to work with a PDF editing tool that supports this level of manipulation.
• If the signature has been flattened into the PDF — A flattened signature is merged into the document's base layer. In this case, you'd need a PDF editor that can redact or cover content, then re-export. WriteGenius's PDF Editor is a good starting point for basic edits like this without needing to buy professional software.

Important: Removing someone else's signature from a legal document without authorization raises serious ethical and legal concerns. Only remove signatures from documents you own or have explicit permission to edit.

Quick Tips for a Professional-Looking Signature

• Match the ink color — Most signatures are black or dark blue. Avoid red or other colors unless there's a specific reason.
• Size it correctly — A signature that's too large looks sloppy; too small looks like you weren't paying attention. Aim to fill the signature line naturally.
• Always review the document before signing — Sounds obvious, but it's worth saying. If the document is long, use a Summarizer to get the key points quickly before you commit your signature.
• Save a backup — Keep an unsigned copy of the document in case you need to re-sign or share it again later.
• Check if the PDF is fillable — Some PDFs have designated signature fields that make placing your signature much easier. If the field isn't working, the PDF may be locked or protected.

Need to Do More with Your PDFs?

Signing is just one piece of the PDF puzzle. If you regularly work with PDF documents — combining files, editing text, or formatting content — it's worth having the right tools in your corner. WriteGenius's PDF Editor handles a range of common PDF tasks right in your browser, and the Merge PDF tool lets you combine multiple documents into one before sending them off for signature.

No installations, no subscriptions required — just practical tools when you need them.

The Bottom Line

Adding a signature to a PDF is genuinely easy once you know which method fits your device and workflow. Mac users can use Preview, Windows users have Adobe Acrobat Reader, mobile users can rely on built-in markup tools, and anyone can use a browser-based PDF editor to get the job done without installing a thing.

The next time someone sends you a contract or form, you won't need to print a single page. Just open, sign, and send — all digitally.