Protect PDF
Add password to PDF file
Last updated:PDF password protection adds an open-password to a PDF using RC4 128-bit encryption — the format every standard PDF reader supports. LlamaPDF encrypts the file entirely in your browser, so the password is never transmitted to a server. Anyone opening the file afterward must enter the password to view its contents.
Drag & drop your file here
or click to choose
Max 50 MB · No registration needed
Your file stays on your device — never uploaded
How to password-protect a PDF
- 1
Upload your PDF file by dragging it into the box above or clicking to browse your files.
- 2
Enter a strong password and confirm it. Choose your preferred encryption level — AES-128 for standard protection or AES-256 for maximum security.
- 3
Click Protect and download your encrypted PDF. The encryption happens entirely in your browser — your password and file never leave your device.
Why use our PDF protector?
Sharing confidential documents like contracts, financial reports, or medical records without encryption puts sensitive information at risk. Adding a password ensures only authorized recipients can open your PDF. LlamaPDF applies encryption directly in your browser using industry-standard AES technology — the same encryption used by banks and government agencies. Unlike other tools that require you to upload sensitive files to their servers, your document never leaves your device.
The tool works on any device — desktop, tablet, or phone — with no software to install. Need to do the opposite? Use our PDF unlocker to remove a password you already know. You can also add a watermark for visual protection or compress your PDF before sharing.
What is PDF encryption?
PDF encryption scrambles a document's contents using a mathematical algorithm so only someone with the correct password can read it. The PDF standard supports two encryption levels: AES-128, which is fast and suitable for everyday documents, and AES-256, which provides stronger protection for highly sensitive files. Once encrypted, the PDF cannot be opened, printed, or copied without the password — even if the file is intercepted during transfer.