Free PDF Password Protect Online
Add a password to any PDF file so it can only be opened with the correct password. Encryption runs entirely in your browser using pdf-lib — your file is never uploaded to a server.
Drop PDF here or browse
PDF files only · Max 100 MB
About PDF Protect
This tool uses pdf-lib to apply AES-128 encryption to your PDF, setting a user (open) password. Anyone who tries to open the protected PDF will need to provide the password. Your file and password are processed entirely in your browser and never sent to any server.
How to Password-Protect a PDF
Upload PDF
Click or drag-drop the PDF you want to protect.
Set Password
Enter your desired password and confirm it in the second field.
Protect
Click "Protect PDF". Encryption is applied client-side instantly.
Download
Download your password-protected PDF. Keep your password safe!
Frequently Asked Questions
pdf-lib applies AES-128 (RC4-128) encryption compatible with Acrobat 5 and later versions.
No — we do not store any passwords. Keep your password in a safe place. If you lose it you will not be able to open the protected file.