PDFBULL
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Protect PDF

Add a password so the PDF can't be opened without one.

Takes
PDF × 1
Returns
PDF × 1

Runs in your browser

Drop a PDF here

Nothing is uploaded. The PDF and your password stay in this tab.

A document that gets forwarded shouldn't be readable by whoever receives it next. Set a password and the PDF can't be opened without it.

How it works

Using Protect PDF, step by step

  1. 01

    Drop in a PDF.

  2. 02

    Choose a password and type it a second time to confirm.

  3. 03

    Protect, then download the password-protected PDF.

What you can do

What people use it for

  • Email a payslip, contract or medical letter.
  • Share a document that shouldn't be readable if the message is forwarded.
  • Add a password before uploading somewhere other people can browse.
Files and processing

What goes in, and where it goes

What it accepts
One PDF at a time, and a password of up to 32 standard Latin characters. That limit isn't ours — the PDF password standard only uses the first 32 characters, and can't represent emoji or non-Latin scripts.
What you get back
One PDF that any reader will ask a password for before opening. The pages, their order, their size and their content are unchanged — only access to them is.
Where your file is processed
Protect PDF runs in your browser. The file and the password are both used only inside this tab: the password derives the encryption key and is then gone, and neither it nor the file is ever uploaded. Nothing is kept once you close the tab.
Questions

Common questions

What encryption is used?

AES-128, using the PDF standard security handler at revision 4. That's a widely supported standard every current PDF reader can open, and the strength of the result still depends on the password you choose.

What if I forget the password?

It can't be recovered. The password is used in your browser and never reaches PDFBull, so there is nothing on our side to look it up in.

Can I remove a password from a PDF?

Yes, with Unlock PDF — but only if you already know the password. This tool only adds one, and rejects a file that is already protected rather than re-encrypting it.

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