Why password-protect a PDF?
Password-protected PDFs require the password to open. This protects:
- Confidential contracts before sharing by email
- Financial statements sent to accountants
- Medical records or personal identification documents
- Any file you want to ensure only the recipient can read
What is AES-256 encryption?
AES-256 (Advanced Encryption Standard with a 256-bit key) is a widely used, standardised cipher for protecting sensitive data. A correctly encrypted PDF cannot be read without the password, even if someone intercepts the file.
How to password-protect a PDF free
- Open the Encrypt PDF tool.
- Drop your PDF onto the upload zone.
- Enter your password in the Password field.
- Re-enter it in Confirm password to avoid typos.
- Click Encrypt PDF.
- Download the protected PDF.
The output file will require the password to open in any PDF reader (Adobe Acrobat, Chrome, iOS Files, etc.).
Important: store your password safely
If you forget the password, the file cannot be recovered. Write the password down somewhere safe, or use a password manager like Bitwarden (free) or 1Password.
Is my password sent to a server?
No. The encryption runs entirely in your browser using a WebAssembly build of qpdf, a widely-used open-source PDF tool. Your password and your file never leave your device.
What if I want to remove the password later?
Open the PDF in your browser (Chrome, Firefox, Edge), enter the password, and use File → Print → Save as PDF without a password set. This removes the password protection.