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Protect PDF

Add a password to a PDF so it can only be opened by someone who has it. Your file is encrypted with AES-256 entirely in your browser — it is never uploaded or stored. Your password is used to encrypt the file on this device and is never kept.

01 Protection no file

Drop a PDF to protect

Set a password and download an AES-256 encrypted copy.

AES-256password required to open
RunAES-256 encryption
02 Output Idle preview

A padlock drops onto a document and clasps shut as a progress bar fills to 100 percent, then a Download button appears. Everything runs in your browser; the file is never uploaded. Your protected file appears here after you run it.

phase preview
add a PDF to protect
Encrypted locally — never uploaded

Lock down a PDF so only the right people can open it. Utilitly encrypts your document with AES-256 — the same standard used by banks and governments — and requires a password to open the file. Your PDF is encrypted right in your browser — it is never uploaded and stays entirely on your device.

How to Password-Protect a PDF

  1. 1
    Add your PDF
    Drag and drop your file into the tool, or click to select it.
  2. 2
    Set a password
    Choose a strong password — at least 12 characters with mixed case, a number, and a symbol — and confirm it.
  3. 3
    Encrypt and download
    Apply AES-256 protection and download your password-protected PDF. Your file never leaves your browser.

About This Tool

Utilitly's Protect PDF tool adds password encryption to a PDF so it can't be opened without the password you set. The file is encrypted inside your browser by qpdf compiled to WebAssembly — it is never uploaded and never stored. The password you choose is checked in your browser as you type and is only ever used, on this device, to encrypt the file.

AES-256 encryption

Your document is protected with AES-256 (Advanced Encryption Standard, 256-bit) — a widely trusted, industry-standard algorithm used to secure sensitive data across finance and government. To keep protection meaningful, the tool asks for a strong password: at least 12 characters, with upper- and lower-case letters, a number, and a special character.

A password to open the file

This tool sets an open password: the document can't be opened at all without it, which is the strongest protection there is. If you also need to remove a password from a file you own, use the Unlock PDF tool. Because the encryption is real, there's no back door — if the password is lost, the file can't be recovered, so store it somewhere safe.

Encrypted in your browser — never uploaded

Your PDF and password never leave the tab. The encryption engine is downloaded to your browser and runs there, so there is no upload to intercept and no copy to delete. If you've searched for how to password-protect a PDF online, this does it without your file going anywhere.

Why protect PDFs with Utilitly

Common reasons to protect a PDF

Frequently Asked Questions

What encryption standard does Utilitly use?

AES-256 (Advanced Encryption Standard with a 256-bit key), the standard PDF password encryption used to protect sensitive data across finance and government.

Can I restrict printing, copying, or editing?

This tool adds an open password, so the document can't be opened at all without it — the strongest restriction there is. It doesn't set separate print-only or copy-only permission flags.

Is my file uploaded to a server to be encrypted?

No. Encryption runs entirely in your browser using qpdf compiled to WebAssembly. Neither your file nor your password is uploaded, and nothing is stored. You can confirm it by opening your browser's Network tab during a run, or by going offline before you press Protect.

What makes a strong password here?

The tool requires at least 12 characters, including an upper-case letter, a lower-case letter, a number, and a special character — enough to keep the protection meaningful. Your password is checked in the browser as you type, used there to encrypt the file, and never stored or transmitted.

What happens if I forget the password?

There's no back door — that's the point of real encryption. If you lose the password, the document can't be opened, so store it somewhere safe.

Can I remove the password later?

Yes. If you know the password, you can remove it anytime with our Unlock PDF tool.

Is it safe to protect a confidential PDF online?

Your file never leaves your device, so there is no upload to intercept and nothing to delete afterwards. For an extra-sensitive document, protect a copy and keep the password somewhere safe.

Is there a watermark on the protected PDF?

No. Your encrypted file comes out clean, with no Utilitly branding.

Related tools

Unlock PDF
Remove a password from a PDF you own and have the password to.
Watermark PDF
Stamp a text or image watermark across your PDF pages.
Sign PDF
Add a signature to a PDF right in your browser.
Compress PDF
Shrink a large PDF's file size.
Password Protect a PDF — AES-256 Encryption | Utilitly