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MyPDFToolbox

Protect PDF

Server-side

Encrypt a PDF with a password so it can only be opened by people who know it.

Processed securely on our server · Options are saved only in this browser, if you allow it — never your files

This tool needs our server: your file is sent over an encrypted connection, processed in memory and deleted immediately. It is never stored or logged.

Drag and drop your PDF here

or

Up to 25 MB per file · Your files never leave your device.

With the password, people can…

Restrictions are respected by most PDF readers, but some programs ignore them.

What does Protect PDF do?

Protect PDF encrypts a document with a password of your choice. From then on, any PDF reader asks for that password before showing a single page. It is the simplest way to send payslips, medical results, contracts or tax documents by e-mail or to store them in shared folders without exposing their contents to anyone who intercepts or finds the file.

Strong, standard encryption

Files are encrypted with AES-256, the strongest method defined by the PDF standard (security handler revision 6), and supported by Adobe Acrobat, the PDF viewers in Chrome, Edge and Firefox, macOS Preview and current mobile apps. Optionally, you can also restrict what people who open the file may do: print it, copy text and images, or edit it and fill in forms.

Why this tool uses our server – and how your file is treated

Most tools on this site run entirely in your browser. Writing AES-256 encrypted PDFs, however, requires the qpdf library, which is not available in browsers, so this tool sends the document to our server over an encrypted HTTPS connection. There it is processed in memory and discarded as soon as the response is sent: it is not written to disk, not logged and not kept. Your original file name is not even transmitted. Your password is used only for that single operation and never stored, neither on the server nor in your browser.

How to password-protect a PDF

  1. Drop your PDF onto the drop zone or click Choose file (up to 25 MB).
  2. Type a password and repeat it. Use “Show password” to check what you typed.
  3. Choose what people with the password may do: print, copy, edit.
  4. Click Protect PDF and download the encrypted document.

Choosing a good password

  • Longer is better: a phrase of four or five random words is both strong and easy to type.
  • Do not reuse the password of your e-mail or bank.
  • Send the password through a different channel than the file – for example by phone or text message.
  • Keep it somewhere safe: nobody, including us, can recover a forgotten password.

Frequently asked questions

Are the restrictions secure?

The open password is real encryption. Print and copy restrictions, on the other hand, depend on the reader respecting them; most do, but some programs ignore them. Treat them as a clear instruction rather than a lock.

How do I remove the password later?

Use Unlock PDF with the same password.