How to Password Protect a PDF for Free
Add a password to any PDF instantly — secure, private, and entirely in your browser. Protect your sensitive information without Adobe Acrobat.
Step-by-Step Security Guide
Step 1 — Open the Protect PDF tool
Go to our Protect PDF tool. It uses pdf-lib to encrypt the file entirely inside your browser — your PDF is never sent to a server.
Step 2 — Upload your PDF
Drag and drop your PDF into the upload zone, or click to browse. The file loads locally — even massive documents are processed instantly since nothing is transmitted.
Step 3 — Set your password
Type your chosen password in the password field. For strong security, use at least 12 characters combining uppercase, lowercase, numbers, and symbols. Store it somewhere safe: without it, the PDF can't be opened.
Step 4 — Encrypt and download
Click "Protect PDF". The tool applies standard 128-bit RC4 PDF encryption (works in Adobe Reader) and immediately offers the protected version for download. Test it by opening the downloaded file — you'll be prompted for the password.
Frequently asked questions
Can I add a password to a PDF without Adobe Acrobat?
Yes. Our free browser-based tool lets you encrypt any PDF with a password without installing Adobe Acrobat or any other software.
What encryption does the tool use?
The tool uses standard 128-bit RC4 PDF encryption (works in Adobe Reader). It stops casual opening without the password, but it is an older standard and not strong protection for highly sensitive documents.
Does my PDF get uploaded to your servers?
Never. The encryption runs entirely inside your browser. Your PDF never leaves your device.
Protect your sensitive PDF right now
Add a password to any PDF in seconds — completely free, no uploads, no Adobe required.
🔒 Add Password to PDF — Free