About the Protect PDF
Add a password to a PDF so it can only be opened by people who know it. The file is encrypted with AES-256, the strongest encryption the PDF standard offers, and you can also limit printing, copying and editing.
Everything happens in your browser. The PDF and the password are never uploaded, and we never see either of them.
How it works
Your PDF is encrypted with AES-256 (PDF 2.0 encryption, revision 6) right here in your browser. Every page, image, font and form field is encrypted; nothing else about the document changes. Before you get the file, the tool checks that it really needs the password and opens with it.
The optional permissions password lets you block printing, copying or editing for people who open the file with the open password. PDF apps are asked to respect these limits; most do, but some ignore them, so the open password is the real protection.
Assumptions and limits
- If you forget the password, the file cannot be recovered. Keep a copy of the original.
- Files up to 50 MB.
- Opens in current versions of Adobe Acrobat and Reader (X or later), Chrome, Edge, Firefox, Safari and macOS Preview. Very old PDF apps that don't support AES-256 can't open it.
- Passwords can be up to 127 bytes, the limit set by the PDF standard. Letters, numbers, spaces, emoji and non-Latin scripts all work.
- A PDF that already has an open password must be unlocked first (you'll need its password).
Worked examples
Send a payslip by email
Choose the PDF, type a password twice, and download payslip-protected.pdf. Tell the recipient the password by phone or another channel, not in the same email.
Allow reading but not printing
Turn on 'Limit printing, copying or editing', set a different permissions password, and untick 'Allow printing'. People with the open password can read the file; apps that respect restrictions won't print it.
A password that's easy to remember
Four unrelated words such as 'lamp river cotton seven' is long and hard to guess. The strength hint below the field shows how hard a password is to guess.
How to use the Protect PDF
- Choose the PDF. Pick or drop a PDF of up to 50 MB.
- Set the password. Type it twice; optionally add restrictions with a second password.
- Download the protected file. It's encrypted with AES-256 and checked before you get it.
Frequently asked questions
How secure is the encryption?
The file uses AES-256, the strongest encryption in the PDF standard. Its security depends on the password: a long password of several unrelated words is practically impossible to guess, while a short common one can be cracked.
What if I forget the password?
The file cannot be opened or recovered without it, by you, by us or by anyone else. That's what makes the protection real. Keep the original file, or store the password in a password manager.
Is my file or password uploaded?
No. The encryption happens in your browser, on your own device. Neither the PDF nor the password is sent to our server, saved in the page or stored anywhere, so nobody else can see them.
What do the restrictions do?
With a permissions password you can block printing, copying or editing. PDF apps are asked to honour these limits and most do, but some ignore them, so treat restrictions as a polite request and the open password as the lock.
Can I remove the password later?
Yes. Use Unlock PDF and type the password; the tool removes it and gives you an unprotected copy. Without the password it can't be removed, because the tool doesn't crack passwords.
This tool runs entirely in your browser. What you enter or upload stays on your device and is never sent to our servers.