Protect PDF with a Password
Add AES encryption and set permissions.
About Protect PDF with a Password
Encrypt a PDF with a user password (needed to open) and/or an owner password (needed to change permissions), and choose whether printing, copying and annotating are allowed. Encryption happens on your device, so the password is never transmitted.
PDF encryption is genuinely useful and widely misunderstood. The format has two different passwords that do very different things, and only one of them actually protects a document.
Set a password to open the file, restrict what can be done with it, or both — and see plainly which of those is real security.
- Processed on your deviceEverything you open or type here is handled by this page and never uploaded anywhere.
- No queue, no limitsNothing waits on a server, so the only limit is your own hardware.
- No account neededNo sign-up and no email address required.
How Protect PDF with a Password works in your browser
Encryption is applied by pdf-lib in this tab. The document and the password are both read into memory here, the encrypted result is written here, and neither is transmitted anywhere. That matters more for this tool than most: encrypting on a server means uploading the unprotected document first, which is exactly the situation you were trying to avoid.
A user password encrypts the contents. Without it there is nothing to read, because the text is not recoverable — this is real protection and it is the one to set when the document matters.
An owner password leaves the document readable by anyone and sets permission flags for printing, copying, annotating and assembly. Compliant readers honour those flags; readers that choose not to can ignore them, and several do. Treat owner-password restrictions as a clear statement of intent rather than as security, because that is what the specification makes them.
When to use it
Encrypting a document containing bank details or identity papers before emailing it. Protecting a contract sent to several parties, where the password travels by a different channel. Marking a report as not-for-printing where the audience is co-operative and the point is to signal intent. Securing personal records before storing them in a cloud drive you do not entirely trust.
Read more about this
Frequently asked questions
What is the difference between the two passwords?
A user password is needed to open the document at all. An owner password leaves it readable but controls whether printing, copying and annotating are permitted.
Does my password get sent anywhere?
No. Encryption is performed in your browser, so the password and the document both stay on your device.
How strong is the protection?
It applies the encryption defined by the PDF specification, which keeps honest readers out. It is only as strong as the password you choose, so pick a real one.