Everything you need to know about adding password protection to PDF files.
Is this PDF password protector really free?
Yes, 100% free with no hidden fees, no subscription, and no signup required. Use it as many times as you need, with any PDF file, completely free forever.
Is my PDF uploaded to a server?
No. This tool runs entirely in your browser using PDF-lib. Your PDF file is never sent to any server — all encryption happens locally on your own device. Total privacy.
What is the difference between Open and Owner passwords?
The Open password (also called User password) is required to view the PDF. The Owner password (also called Permissions password) controls who can change security settings or override restrictions — useful when you want to share a restricted PDF but retain master control.
Which encryption level should I use?
AES-128 is the best balance of security and compatibility. AES-256 provides maximum security and is recommended for highly sensitive documents. RC4-128 is for compatibility with very old PDF readers (pre-2004).
Will the protected PDF work in all PDF readers?
Yes. The AES-128 encrypted output is compatible with Adobe Acrobat, Adobe Reader, Foxit, Chrome's built-in PDF viewer, macOS Preview, and virtually all modern PDF reading software.
What if I forget the password I set?
There is no way to recover a forgotten PDF password — this is by design as it ensures your security. Always save your password in a secure password manager before locking your PDF.
Does protecting the PDF change its content?
No. Encryption wraps the document — the pages, text, and images inside stay exactly the same. They're simply locked behind your password.
Can I set different permissions for different people?
Permissions apply to the document as a whole, not per person. Anyone who opens it with the password is subject to the same permission settings you chose.
Are the permission restrictions unbreakable?
Permission flags are enforced by the PDF reader, so they're a strong deterrent rather than an absolute barrier. The open password, by contrast, is a true cryptographic lock on the whole file.
Can I protect a PDF that's already encrypted?
No. You'll need to remove the existing protection first, then upload the unprotected copy to apply a new password.
Do I need an owner password?
It's optional. If you leave it blank, the tool derives one automatically so the permission restrictions are enforced. Set your own if you want to retain master control yourself.
How strong should my password be?
Aim for the Strong rating — mix uppercase, lowercase, numbers, and symbols, with at least 8 characters. The live strength meter guides you as you type.
Can I change the settings and protect again?
Yes. Use "Protect Another PDF" or adjust the password, encryption, and permissions, then protect again. The original stays loaded until you clear it.
Is there a file size limit?
There's no hard limit — your device's memory is the practical ceiling. Very large PDFs simply take a little longer to encrypt in the browser.
Does it work offline?
After the page loads once, PDF-lib is cached, so protection usually works on flaky connections. The first visit needs internet to load the library.
What browsers are supported?
All modern Chromium browsers (Chrome, Edge, Brave, Arc, Opera), Firefox, and Safari versions from the past few years work smoothly.
Will my original PDF be changed?
No. The tool reads your PDF and produces a new, encrypted copy. Your original file on disk is never modified.
Can I remove the password later?
Yes, with an unlock/remove-password tool and the correct password. Keep your password safe so you can unlock the file when needed.
Should I send the password with the file?
No. Always share the password through a separate channel — a text or call — rather than in the same email as the protected PDF.
Can I use protected PDFs commercially?
Yes. The protected file is built from your own PDF, so you can use and share it however you like. The tool adds no restrictions, branding, or watermarks.