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Protect PDF

Add a password so only people you trust can open your PDF.

Your files never leave your device.

When to use it

Protect PDF adds a password to a PDF, so only people who know it can open the file. Use it before emailing documents with personal or financial details: tax returns, payslips, bank statements, medical letters, contracts, ID scans and HR records. It’s also useful for files stored on shared drives or USB sticks that could be lost.

How to password-protect a PDF

  1. Tap Choose PDF file, or drag a PDF onto the box.
  2. Type a Password (at least 8 characters; longer is stronger) and enter it again in Repeat password.
  3. Under After opening, people can, choose whether to allow Print the document, Copy text and images and Edit the document.
  4. Press Protect PDF, then Download. The file ends in “-protected.pdf”.
  5. Open the downloaded file once to check the password works before you send it.

A worked example

You need to email your accountant a 6-page PDF of last year’s payslips. Open the file and choose a passphrase like river-lamp-cactus-92, entering it twice. Leave printing allowed, since they’ll need to print, but untick editing. Download “payslips-2025-protected.pdf”, attach it to the email, and text the password to the accountant separately. Anyone who intercepts the email sees only a locked file.

Choosing a good password

  • Use 12 or more characters, or a passphrase of three or four random words.
  • Avoid names, birthdays and common words that can be guessed.
  • Use a different password for each sensitive file or recipient.
  • Store it in a password manager so you can find it later.

Tips

  • Keep an unprotected copy in a secure place, in case the password is lost.
  • Check the size and order first; after protection, the file can’t be edited by other tools until it’s unlocked.
  • Tell the recipient to expect a password, so they don’t think the file is broken.

Common mistakes

  • Sending the password in the same email as the file.
  • Using a short or obvious password, which can be cracked by guessing programs.
  • Relying on “no copying” alone to protect secrets; the open password is what really protects the content.
  • Protecting a file you still need to change. Make your edits first.

Private by design

Your PDF and password stay on your device. Encryption happens in your browser, nothing is uploaded, and this page loads no ad scripts.

Remove a password you know with Unlock PDF, generate a strong password with the Password Generator, or mark copies with Watermark PDF.

Frequently asked questions

How secure is the protection?

The PDF is encrypted with AES-256, the strongest encryption PDF supports. Without the password, the content can't be read. Security then depends on your password, so use a long one that isn't used anywhere else.

What if I forget the password?

Nobody can open the file, including toolwise, because the password is never stored or sent anywhere. Keep the unprotected original somewhere safe, or save the password in a password manager.

What do the permission options do?

They ask PDF readers to allow or block printing, copying text and images, and editing once the file is open. Most readers respect them, but they're weaker than the open password, so don't rely on them alone for secrets.

How do I send the password safely?

Send it a different way from the file, for example by text message or phone call if the PDF goes by email. Never put the password in the same email as the attachment.

Is my PDF or password uploaded?

No. Encryption happens in your browser. This page also loads no advertising scripts.

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