Protect PDF
Add a password to a PDF with AES-256 encryption — set an open password (and an optional separate owner password), then download. Runs entirely in your browser; your file is never uploaded.
Input
Controls permissions (printing, editing). Leave blank to use the same password for both.
Protected PDF
Add a PDF, set a password, and press Protect PDF. The encrypted file is built in your browser — download it when you're ready.
Guides
Protect PDF adds a password to a PDF file with AES-256 encryption, right in your browser. Set a password, and optionally a separate owner password, then download an encrypted copy — no signup, no watermark, and your file never leaves your device.
How to use it
- Drop or browse for a PDF file.
- Enter a password and confirm it.
- Optionally set a separate owner password to control permissions like printing or editing. Leave it blank to use the same password for both.
- Press Protect PDF. The encrypted file downloads automatically as
protected.pdf.
What's the difference between the password and the owner password?
The password (sometimes called the "user" or "open" password) is required to open and view the PDF at all. The owner password controls what someone can do once the file is open — for example, whether they can print or edit it — without necessarily requiring a separate password to open it. Most people only need the first password; leave the owner password blank and iotools uses the same password for both, which is the common case.
Why protect a PDF in the browser?
Most online PDF password tools upload your document to a server to encrypt it. This one does the whole job locally using qpdf compiled to WebAssembly, so contracts, statements, and anything else sensitive stay on your computer. There's no upload or download round-trip, so protecting even a large PDF is near-instant.
What encryption does this use?
AES-256, the strongest encryption level qpdf supports and the current PDF standard for password protection. Files encrypted this way require the correct password to open in any modern PDF reader, including Adobe Acrobat, Preview, and browser PDF viewers.
Will I be able to remove the password later?
Yes — use the companion Unlock PDF tool with the password you set here to remove the encryption and get back an open, unprotected copy.
What if I forget the password?
There's no way to recover it. Because the file is encrypted with your password and never uploaded anywhere, iotools has no copy of it and no way to reset or bypass it. Store your password somewhere safe before closing the tab.
Your file is processed entirely on your device and is never uploaded.