Protect PDF
Add a password to keep a PDF private.
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About Protect PDF
Protect PDF adds a strong password to a PDF so only people who know it can open the file — encrypted with AES-256, right in your browser. You can also optionally restrict printing, copying and editing.
Your file and password never leave your device; everything runs locally. It's free, with no sign-up and no watermark.
Frequently asked questions
- Is Protect PDF free?
- Yes — completely free with no sign-up, no watermark, and no limits.
- Is my PDF or password uploaded to a server?
- No. The PDF is encrypted entirely in your browser using your device's built-in cryptography, so neither the file nor the password ever leaves your device.
- How strong is the protection?
- It uses AES-256 encryption — the strongest standard PDF encryption, the same class used by banks and governments.
- What's the difference between the open password and the owner password?
- The open password is required to view the PDF at all. The optional owner password lets you also set permissions — for example allowing viewing but blocking printing or copying — while keeping the ability to change those settings.
- Can I recover the password if I forget it?
- No. There is no back door — if the password is lost, the PDF can't be opened. Store it somewhere safe.
- Can I remove the password later?
- Yes, as long as you know it: open the PDF with the password in any viewer. Note that our Unlock PDF tool only removes owner-permission restrictions, not a password required just to open the file.