Strong AES-256 encryption
Your PDF is encrypted with the same 256-bit AES standard used to secure sensitive files, so the password is the only way in.
Protect PDF
Lock a PDF with a password — encrypted on your device, not a server.
or drop a file here
Files are processed in your browser and never uploaded.
Protect PDF online — free and private
Protect PDF adds a password to your document and encrypts it with strong AES-256 encryption, so only people who know the password can open it. It is the simplest way to keep contracts, statements, medical records and other private files safe before you email or share them.
The encryption is applied entirely inside your browser using qpdf compiled to WebAssembly, which means your file and your password never leave your device — unlike online tools that upload your document to encrypt it on a server. Already have a protected file? Drop it in and the tool will offer to change its password: enter the current one, pick a new one, and it swaps them in a single step. To remove a password you know instead, use Unlock PDF.
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Why use PDF10x to protect pdf?
Nothing leaves your device
Encryption runs locally in your browser. Your document and the password you choose are never uploaded or stored anywhere.
Opens everywhere
The protected file prompts for the password in every standard PDF reader — Acrobat, browsers, phones and more.
How to protect pdf online
- 1
Select or drop the PDF you want to protect.
- 2
Type the password you want to set.
- 3
Click “Protect PDF” to encrypt it in your browser.
- 4
Download the password-protected PDF and share it safely.
Frequently asked questions
What happens if I forget the password?
There is no way to recover it — that is the point of strong encryption. Keep your original, unprotected file somewhere safe, or store the password in a password manager, so you are never locked out.
Is my password or file uploaded?
No. Both the encryption and the password stay in your browser. Nothing is sent to a server, which is what makes this safe for confidential documents.
How strong is the encryption?
PDF10x uses 256-bit AES encryption, the strongest standard supported by the PDF format and widely used to protect sensitive data.
Can I change the password on a PDF that is already protected?
Yes. Select the protected file and the tool will ask for its current password alongside the new one, then swap the old password for the new one in a single step. You need the current password to do this.
Can I remove the password later?
Yes. As long as you know the password, the Unlock PDF tool removes it and gives you an unprotected copy.