01
A confidential contract
Uploading a contract PDF and setting a password produces a downloaded copy that won't open in any PDF reader without that exact password.
Protect PDF
PDF ToolsPassword protect a PDF with AES-256 encryption online — free PDF protector.
PDF file
About
About the Protect PDF
Adds a password to a PDF with strong AES-256 encryption, right in your browser, so it can only be opened by someone who knows the password.
Businesses use it to password-protect a confidential contract or financial document before emailing it, while individuals use it to lock down a PDF containing personal or sensitive information. It's one of many free PDF tools on Toolapt, and like every tool here, it's free to use with no sign-up and no limit on how many times you run it.
Examples
Protect PDF examples
3 worked examples
02
A financial statement before emailing
Protecting a bank statement PDF with a password before emailing it adds a layer of security beyond the email account itself.
03
Reversing it later
A PDF protected here with the password "budget2026" can later be opened up again with the Unlock PDF tool by entering that same password.
Related tools
FAQ
Frequently asked questions
Quick answers to common questions about the Protect PDF.
What does Protect PDF do?
It encrypts a PDF with AES-256 and a password you choose, so it can only be opened by someone who knows that password.
Is Protect PDF free to use?
Yes. It's free, with no sign-up, no watermark and no limit on how many files you protect.
Is my file safe when I use this tool?
Yes. The encryption runs entirely in your browser, so neither the PDF nor the password you choose ever leaves your device — nothing is uploaded, stored or seen by anyone.
How strong is the protection?
The PDF is encrypted with AES-256 (PDF 2.0 / Acrobat X standard), the strongest option PDFs support. How safe it is in practice depends on your password — use a long one that isn't easy to guess.
What happens if I forget the password I set?
There's no way to recover it — the whole point of real encryption is that the file can't be opened without the correct password, including by us. Keep a copy of the password somewhere safe.
How do I remove the password later?
Use the Unlock PDF tool, entering the same password, to produce a copy that opens without one.
Can I use Protect PDF on my phone?
Yes. The page is fully responsive and works on mobile, tablet and desktop browsers alike.
Does Protect PDF have any limitations?
It applies password protection to the whole document; it doesn't offer separate permissions like print-only or view-only access levels. Very old PDF readers (from before 2010) may not support AES-256. A PDF that already has a password must be unlocked first.