Protect PDF adds a password to your PDF using strong AES-256 encryption, so only people who know the password can open it. It is free, quick and works on any computer or phone.
How to password protect a PDF
- Click "Choose PDF file" or drag and drop a PDF into the box.
- Type a password twice.
- Choose whether printing, copying and editing are allowed.
- Click "Protect PDF" and then "Download PDF".
Why use ZentaPDF Protect PDF?
Easy to useSimple steps, clear buttons — done in a few clicks.
Free, no sign-upNo account, no email, no watermark and no daily limits.
FastNo waiting — results are ready in seconds.
Works everywhereUse it on Windows, Mac, Linux, Android or iPhone in any modern browser.
Original qualityPages are copied as they are — text and images stay crisp.
Large filesHandle big files and many pages — limited only by your device’s memory.
Frequently asked questions
How strong is the protection?
Files are encrypted with AES-256, the strongest standard PDF encryption, supported by Adobe Reader and all modern PDF apps.
What if I forget the password?
The file cannot be opened without it — not by us or anyone else. Keep your password somewhere safe.
Is my password sent anywhere?
No.
Is it really free? Do you add a watermark?
Yes, it is completely free with no sign-up, no watermark and no daily limits. The site is supported by a few non-intrusive ads.
Guides
- How to Password Protect a PDF – Free and Secure
- How to Sign a PDF Without Printing It
- How to Remove a Password from a PDF – Bank Statements, Payslips and More
Related tools
Unlock PDFRemove the password from a PDF when you know it.Add WatermarkStamp text or an image over your PDF pages.Flatten PDFMake filled-in form fields part of the page so they can’t be changed.Merge PDFCombine several PDF files into one document, in the order you want.