Password Protect PDF
Lock your PDF with a password using AES-256 encryption, right in your browser.
- ✓Files never uploaded
- ✓No file limits
- ✓No sign-up
- ✓No watermark
How to Protect PDF
- 1Drop your PDF into the box or click to choose it.
- 2Enter a password and type it again to confirm.
- 3Click Protect PDF and download the encrypted file.
Why pdfdots?
Private by design
All processing happens locally in your browser. Your documents are never uploaded to a server, so nobody else can see them.
No limits
No daily task caps, no file-count limits and no premium tier. Process as many PDFs as your device can handle.
Fast
There's no upload or download queue. Work starts the moment you drop a file and finishes at the speed of your own computer.
Works everywhere
Windows, Mac, Linux, iPhone, Android or Chromebook — if it has a modern browser, pdfdots runs on it. Nothing to install.
Keep sensitive PDFs private with a password
Bank statements, contracts, medical records and HR documents often travel by email or sit in shared folders where the wrong person could open them. Adding a password means anyone who opens the PDF must enter it first. This tool encrypts the file with AES-256, the strongest encryption the PDF format supports and the same standard used by banks and governments.
The encryption is done by qpdf, a well-established open-source PDF library, running directly in your browser through WebAssembly. That means the unprotected file is never uploaded to a server — not ours, not anyone's. The encrypted PDF opens normally in Adobe Acrobat, Preview, Chrome, Edge and other modern readers once the password is entered.
Choose a strong password: long, unique and not easy to guess, ideally a passphrase of several words. Share it through a different channel than the file itself, for example send the PDF by email and the password by text message. Keep it somewhere safe, because we never see or store your password and cannot recover it if you forget it. If you lose it, the only option is to protect the original file again with a new one.
Our take
We add a password before sending documents through channels we do not fully control: payslips shared with an accountant by email, a medical report uploaded to a shared drive, or tax papers on a USB stick.
We choose a long passphrase rather than a short complex password, and we send it through a different channel than the file, for example by phone or text message. Sending the password in the same email defeats the purpose.
The pitfall we see is forgetting the password; there is no recovery, and that is the point of encryption. Keep it in a password manager. If you only want to signal that a file is confidential rather than lock it, Add Watermark is the lighter tool, and for removing a known password later, use Unlock PDF.
Related tools
Frequently asked questions
How strong is the encryption?+
The PDF is encrypted with AES-256, the strongest standard encryption available for PDF files.
Is my file uploaded to protect it?+
No. Encryption runs locally in your browser with qpdf compiled to WebAssembly.
What if I forget the password?+
We can't recover it, because we never see or store it. Keep your password somewhere safe.
Will the protected PDF open everywhere?+
Yes. Modern readers like Acrobat, Preview, Chrome and Edge open it after the password is entered.
Can I remove the password later?+
Yes. Use our Unlock PDF tool and enter the current password.
Is it free?+
Yes. No sign-up, no limits and no watermark.