Protect PDF
Encrypt a PDF with a password online for free. Set printing, copying, and editing permissions before sharing, encryption happens in your browser.
About This Tool
Lock a PDF so it can only be opened with a password, and decide what readers may do once it is open. Printing, copying text and editing are separate switches, so you can share a document for reading without letting it be altered. The encryption happens entirely in your browser, your file and your password never travel over the network.
How To Use
- Drop your PDF into the upload zone or click to select it.
- Type the password you want to set and choose the permissions to allow.
- Click "Protect" and download the encrypted PDF.
How It Works
The PDF is encrypted using the standard security handler built into the PDF format. Every content stream and string in the file is encrypted with a key derived from your password, so the bytes on disk are unreadable without it. Any compliant reader, Acrobat, Preview, Chrome, will ask for the password before rendering a single page.
Permissions are stored as flags inside the encryption dictionary. Readers honour them to decide whether the print button, text selection or editing tools are available. They are enforced by the reader rather than by cryptography, so treat them as a clear statement of intent rather than an unbreakable lock; the password itself is the real protection.
Encryption runs in a Web Worker on your own machine. The password is used to derive the key and is then discarded, it is never stored, logged or transmitted. If you forget it, nobody can recover the file for you, so keep a copy somewhere safe.
Frequently Asked Questions
Can you recover my password later?
No. The password never leaves your browser and is not stored anywhere, so nobody, including us, can unlock the file for you. Save it in a password manager.
How strong is the encryption?
The file uses the PDF standard security handler with AES encryption. The real limit is your password: a short, common one can be brute-forced, a long random one cannot.
What do the permission switches do?
They tell PDF readers whether printing, copying text or editing should be offered. Well-behaved readers respect them; the password is what actually keeps people out.
Can I remove the password later?
Yes, use the Unlock PDF tool with the same password to save an unprotected copy.
Does it work on every PDF?
It works on any PDF that is not already encrypted. If your file already has a password, unlock it first, then protect it again with the new one.