Protecting a PDF with a password prevents unauthorised people from opening it. Whether you are sending a confidential report, a private contract, or sensitive personal data, adding a password to your PDF is a quick way to add a layer of security. This guide shows you how to do it for free.
Method 1: Free Browser-Based PDF Encryptor (No Upload, AES-128)
PDFWonder's Protect PDF tool encrypts your PDF with AES-128 entirely in your browser. Your file and password are never sent to any server.
- Go to the Protect PDF tool.
- Upload your PDF.
- Enter a user password (required to open the PDF).
- Optionally enter an owner password (controls editing/printing permissions).
- Click Encrypt & Download.
- The encrypted PDF is downloaded to your device.
Method 2: Password Protect a PDF in Adobe Acrobat
Adobe Acrobat Pro (paid) gives the most control:
- Open your PDF in Adobe Acrobat.
- Go to File → Properties → Security tab.
- Change the Security Method to Password Security.
- Check Require a password to open the document.
- Enter your password, set permissions, and click OK.
- Save the PDF.
Acrobat also lets you restrict copying, printing, and editing separately from the open password, giving granular control.
Method 3: Password Protect PDF in Microsoft Word (Before Exporting)
If you are creating the document in Word first, you can add a password during the PDF export:
- Go to File → Save As → Browse.
- Change the file type to PDF.
- Click Options.
- Check Encrypt the document with a password.
- Enter and confirm your password.
- Click OK and Save.
Method 4: Password Protect PDF on Mac
- Open the PDF in Preview.
- Go to File → Export as PDF.
- Check Encrypt.
- Enter and verify the password.
- Click Save.
Choosing a Strong PDF Password
A strong PDF password should be:
- At least 12 characters long — longer passwords are exponentially harder to crack
- A mix of uppercase, lowercase, numbers, and symbols — e.g., "Tr0ub4dor&3" is much stronger than "password123"
- Not a dictionary word or common phrase — dictionary attacks can crack simple passwords quickly
- Unique — do not reuse passwords across multiple protected PDFs or accounts
Store the password securely in a password manager (like Bitwarden or 1Password). If you lose it, the encrypted PDF cannot be recovered.
What Permissions Can You Set on a Password-Protected PDF?
Beyond the open password, PDF encryption allows you to control what authenticated users can do:
- Printing: Allow high-resolution printing, low-resolution printing, or no printing
- Copying text: Allow or block the ability to select and copy text from the PDF
- Editing: Block users from modifying the content, even after opening
- Form filling: Allow or restrict filling in interactive form fields
- Annotating: Allow or restrict adding comments and annotations
Our browser-based tool applies sensible defaults: printing is allowed at high resolution, but copying and editing are restricted to protect your content.
How to Remove a Password From a PDF
If you need to unlock a PDF you own (and you know the password):
- Open the password-protected PDF in Chrome or Edge.
- Enter the password when prompted.
- Press Ctrl+P (or Cmd+P on Mac) to open the print dialog.
- Change the printer/destination to Save as PDF.
- Click Save — the new PDF will be unprotected.
Frequently Asked Questions
How do I password protect a PDF for free?
Use PDFWonder's free Protect PDF tool. Upload your PDF, enter a password, and download the encrypted PDF. Encryption is done entirely in your browser with AES-128 — your file and password are never sent to any server.
What encryption does the PDF password use?
PDFWonder uses AES-128 encryption, the same standard used by Adobe Acrobat and professional PDF software. AES-128 is widely accepted as highly secure.
Can someone remove the password from my PDF?
If someone knows the correct password, they can remove it using a PDF tool. Without the password, a properly AES-128-encrypted PDF cannot be practically recovered by brute force for typical password lengths.
What is the difference between user password and owner password?
The user password is required to open the PDF. The owner password controls what the user can do after opening — such as printing, copying text, or editing. Both can be set; the owner password defaults to the user password if not specified separately.
How do I remove a password from a PDF?
Open the password-protected PDF in your browser (Chrome, Edge) which will prompt for the password. After entering it, print to PDF (Ctrl+P → Save as PDF) to get an unprotected copy.
Is my PDF password stored by PDFWonder?
No. Your password is only used inside your browser to encrypt the PDF using pdf-lib. It is never transmitted to any server or stored anywhere. Once you close the tab, it is gone.