Protect PDF with a password
Encrypt a PDF with a password using AES-256. Free and secure — your file and password never leave your device.
- Upload
- Options
- Download
- ✓ 100% free
- ✓ No sign-up
- ✓ No limits
- 🔒 Files never leave your device
How to: Protect PDF
- Select your PDF.
- Enter and confirm a password.
- Click Start and download the encrypted PDF.
Adding a password stops anyone without it from opening your PDF. FreePDF encrypts files with AES-256 locally, so neither the file nor the password is ever sent over the internet.
Common uses
- Email salary slips, bank statements or medical reports safely.
- Share ID documents with a password sent separately.
- Protect business proposals and contracts.
Tips for best results
- Use a long password – try our Password Generator.
- Share the password through a different channel than the file.
How PDF encryption works
AES-256 is the strongest encryption defined in the PDF standard and is supported by Adobe Reader, Chrome, Edge, Firefox, macOS Preview and modern mobile viewers. Without the password, the content cannot be read.
Choosing a strong password
Use at least 12–16 characters mixing words, numbers and symbols. A passphrase like “Coffee-Window-42-Orbit” is both strong and memorable. Never send the password in the same email as the file.
Works offline
Encryption happens in your browser, so you can protect files even without an internet connection once the page has loaded.
Why use FreePDF for Protect PDF?
| FreePDF | Typical upload-based sites | |
|---|---|---|
| Files uploaded to a server | No – processed on your device | Yes |
| Sign-up required | Never | Often for bigger jobs |
| Hourly / daily task limits | None | Common on free plans |
| Watermark on output | Never | Sometimes |
| Works offline after loading | Yes, for most tools | No |
Frequently asked questions
How strong is the encryption?
Files are encrypted with AES-256, the strongest standard PDF encryption.
Is Protect PDF really free?
Yes. Every tool on FreePDF is 100% free with no file limits, no sign-up and no watermarks. The site is supported by unobtrusive ads.
Are my files uploaded to a server?
No. FreePDF processes your files directly in your browser using JavaScript. Your documents never leave your device, so they stay completely private.
Does it work on mobile?
Yes. FreePDF works in any modern browser on Android, iPhone, iPad, Windows, Mac and Linux.