How to Password Protect a PDF (Free Methods)

Published: June 2026 · 5 min read

You have a confidential PDF – a contract, a financial statement, or personal records – and you need to lock it with a password before sharing it. Adobe Acrobat charges a subscription for that feature, but you don't have to pay. You can password protect a PDF for free using tools already on your computer or freely available online. This guide covers the best free methods, and explains which approach keeps your data most secure.

Why PDFcone Doesn't Have a Password Protection Tool (Yet)

At PDFcone, our tools run entirely in your browser – your files never leave your device. That's great for privacy, but it also means we can't offer password protection. Client‑side PDF encryption is extremely complex and isn't supported by the JavaScript libraries we use. We'll announce it on our blog if that changes. In the meantime, the methods below are the safest, most reliable free options.

Method 1: Use LibreOffice (Windows, Mac, Linux – Completely Free)

LibreOffice is a free, open‑source office suite that includes a built‑in PDF export with encryption. It works on all major operating systems and requires no internet connection.

1. Download and install LibreOffice from libreoffice.org (free, no ads).
2. Open your PDF – LibreOffice Draw can open PDF files and let you edit them, but you don't need to change anything.
3. Export as PDF – Go to File → Export As → Export as PDF…
4. Set a password – In the export dialog, click the "Security" tab. Check "Encrypt with a password" and enter your password twice.
5. Save – Choose a location and click Export. The resulting PDF will require the password to open.

This method is 100% offline, so your file never leaves your computer. It's the most private way to add a password.

Method 2: Use Apple Preview (Mac – Built‑In and Free)

If you're on a Mac, the built‑in Preview app can password‑protect PDFs without any extra software.

1. Open your PDF in Preview (double‑click it).
2. Export with password – Go to File → Export… (not "Export as PDF", just "Export").
3. Check "Encrypt" – In the save dialog, tick the box labeled "Encrypt" and enter a password.
4. Save – Choose a location and click Save. The exported PDF is now protected.

Preview uses AES‑128 encryption, the same standard Adobe uses. It's quick, private, and already installed on every Mac.

Method 3: Use Microsoft Word (Windows – Save as PDF with Password)

If you have Microsoft Word (even an older version), you can password‑protect a PDF via the Save As dialog.

1. Open the PDF in Word – Word can convert PDFs to editable documents (formatting may change slightly).
2. Go to File → Save As → choose PDF as the file type.
3. Click "Options…" – in the save dialog, click the Options button.
4. Check "Encrypt the document with a password" – enter your password twice.
5. Save – the PDF will be encrypted with the password.

This method is slightly less private because the PDF is processed by Word, but it's still offline and doesn't require an internet connection.

What About Free Online Password Protection Tools?

Many websites claim to password‑protect PDFs for free, but they upload your file to their servers. That defeats the purpose of privacy. If the document is sensitive, avoid online tools. Stick with the offline methods above – they're safer, free, and don't require trusting a third party with your data.

Need to Merge, Crop, or Compress First?

PDFcone's tools are perfect for preparing your document before adding a password. Use our free, private tools to:

• Merge PDF – combine multiple files into one.
• Compress PDF – reduce file size for easier sharing.
• Crop PDF – trim unwanted margins and borders.
• Split PDF – extract only the pages you need.

Then, use one of the methods above to lock the final PDF with a password. All PDFcone tools run client‑side, so your files never leave your device.

Frequently Asked Questions