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Upload
Select the PDF file that you want to protect with a password. Your file will be processed locally in your browser.
Files stay secure
Password-Protect PDF Online with AES-256
How to Protect PDF with Password Online Free
Secure your PDF documents by adding password protection in just a few steps
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Set Password
Enter a strong password that will be required to open your PDF. Choose a password that is easy for you to remember but hard for others to guess.
Strong encryption - 3
Download
Download your password-protected PDF file. Your document is now secure and will require the password you set to be opened.
Secure & Private
local processing: files never leave your device
Your password and PDF are processed entirely in your browser. We never see your files or passwords.
Frequently asked questions
Encryption runs locally in your browser using WebAssembly and Web Workers. Your PDF never leaves your device. The app writes an encrypted container around the existing content; pages are unchanged, access requires the password.
AES-256 offers the highest security and broad compatibility with modern viewers. 128-bit is lighter but still strong. Both follow the PDF specification; choose 256-bit when possible for long-term protection.
For 256-bit, AES is always used. For 128-bit you can enable AES-128 (recommended) or use legacy RC4-128 for very old PDF readers. If a viewer refuses to open the file, try 128-bit with RC4.
We do not receive or store your PDFs. All encryption happens on your device only. The page may load anonymous Google analytics, but files are never uploaded to servers.