How to sign a PDF on Mac or Chromebook for free (2026)

On a Mac you already have what you need. On a Chromebook it takes one extra step. Here's how to sign a PDF on either one without uploading it anywhere.

Updated October 2026 · 4 min read

On a Mac

Sign with Preview

1. Open the PDF in Preview (double-click it, or right-click → Open With → Preview).
2. Click the Markup button (the pen tip icon), then the Sign button.
3. Create a signature. You can write with your trackpad, hold a signed sheet of paper up to the camera, or use a nearby iPhone or iPad.
4. Click your signature to place it, then drag and resize it into position.
5. Add the date and your name with the Text tool, then choose File → Save.

Preview keeps your signature, so next time it's two clicks. If the Markup tools are greyed out, the PDF may be password-protected or have editing restricted.

Other options on Mac

Chrome and Safari can both open the PDF, and the Penwise extension works in Chrome on a Mac. Adobe Acrobat Reader (free) has its own Fill & Sign tool if you want to stay out of Preview.

On a Chromebook

Option 1: Chrome's built-in viewer

1. Open the PDF in Chrome. Downloaded files open there by default.
2. If the form is fillable, click a field and type.
3. To sign, use the pen or annotation tool (if your version of ChromeOS shows one) to draw your signature on the page.
4. Save or download the file.

Good for: a quick scribble. Limits: signatures aren't saved, drawing with a trackpad looks rough, and the tools you see vary by ChromeOS version.

Option 2: Penwise (Chrome extension)

Disclosure: we make Penwise.

1. Install Penwise from the Chrome Web Store. It works on ChromeOS like any Chrome extension.
2. Open your PDF, click the Penwise icon, and type into the form fields.
3. Click Sign and draw, type or upload your signature. It's saved for next time.
4. Click where it should go, then Download.

Files are processed in your browser and aren't uploaded. Filling, signing and downloading are free with no watermark.

Option 3: Adobe Fill & Sign Android app

If your Chromebook supports Google Play, you can install Adobe's Fill & Sign app. It handles saved signatures well, though it may ask you to sign in and nudges you toward paid Adobe plans.

Fixes for common problems

• Can't type into the form. It's probably a flat PDF with no real fields. Use a tool that lets you add text boxes anywhere, like Preview's Text tool or Penwise.
• Signature looks jagged. Sign slowly with a trackpad, or write on white paper with a dark pen and use the camera option in Preview.
• It saved, but entries are missing elsewhere. Open the saved file in a second app, such as your phone's viewer, to confirm everything was written into the file.
• The signature has a white box behind it. Re-create it from a cleaner image, or draw it instead of uploading a photo.

Is it legally valid?

In the US (ESIGN, UETA) and the EU (eIDAS), simple electronic signatures like these are generally valid for everyday agreements such as leases, permission slips and offer letters. Some documents, such as certain real-estate, court or notarized papers, need more. This isn't legal advice, so check with whoever sent the document. More background in our guide to signing a PDF without uploading it.

FAQ

Can I sign a PDF on a Mac without any app?

Yes. Preview is built into macOS. Open the PDF, click Markup, then Sign, create a signature and place it on the page.

Can you sign a PDF on a Chromebook for free?

Yes. Chrome's built-in viewer can fill form fields and draw on the page, and free extensions such as Penwise add saved and typed signatures. Adobe's Fill & Sign Android app is another option on Chromebooks with Google Play.

Is my PDF uploaded when I sign it?

Not with Preview, Chrome's viewer or Penwise. They work on your computer. Many online signing websites do upload your file, so check before using one for sensitive documents.

Why can't I type into my PDF?

It's probably a flat PDF, a picture of a form, with no fillable fields. Use a tool that lets you place text boxes anywhere on the page.