How to Password-Protect a PDF File

Lock a PDF before you share it

A password on a PDF means only people who know that password can open it. That's useful when you're emailing a contract, a payslip, a bank statement, medical records, or anything you wouldn't want sitting unprotected in someone's inbox or a shared drive. Instead of trusting the channel, you put the lock on the file itself, so it travels protected wherever it goes.

The Protect PDF tool does this entirely in your browser. Your PDF is read and rewritten on your own device using the browser's built-in PDF engine, so the file never gets uploaded to a server, and there's no account to create. You pick a password, choose an encryption strength, decide what readers are allowed to do (print, copy, edit), and download the protected copy. Below is the exact flow.

How to password-protect a PDF

1. Open the tool. Go to Protect PDF. You'll land on the Upload tab. Nothing leaves your computer at any point in this process.

2. Add your PDF. Drag the file onto the drop zone, or click Select PDF File and pick it from your device. The tool reads the page count and file size locally and then moves you to the Security tab. If you see "Please select a PDF file," the file isn't a valid PDF — check the extension and try again.

3. Set the open password. In the User Password (required to open) field, type the password readers will need to view the document. Use the eye icon to reveal what you typed and avoid typos. Re-enter the same password in Confirm Password — if they don't match, you'll see a red warning and won't be able to continue.

4. Watch the strength meter. As you type, a strength bar shows Weak, Fair, Good, or Strong, with hints for length, uppercase, lowercase, numbers, and symbols. Aim for Strong: at least 8 characters mixing all four. A four-character minimum is enforced, but short passwords are easy to guess, so go longer.

5. (Optional) Add an owner password. The Owner Password is separate from the open password. It grants admin rights to change permissions later. Set it if you want to keep control over what others can do with the file even after they can open it. Leave it blank if you don't need that.

6. Choose the encryption level. Pick 128-bit AES for the widest compatibility with older readers, or 256-bit AES for maximum security (the default). For most sensitive documents, leave it on 256-bit.

7. Set document permissions. In the permissions box, tick or untick what readers may do: printing, copying text, modifications, annotations, and form filling. For example, to share a read-only report, allow printing but turn off copying and modifications.

8. Review the summary. Open the Summary tab to confirm the file name, page count, whether each password is set, the encryption level, and which permissions are Allowed (green) or Denied (red). Catch mistakes here before you generate the file.

9. Generate and download. Click Protect & Download PDF. A progress bar runs through the steps, then the Result tab shows original vs. protected size and your encryption level. Click Download to save the new _protected.pdf copy. Your original file is untouched.

10. Verify it. Close the downloaded PDF and reopen it in your normal reader. You should be prompted for the password you set. Test it before you send the file to anyone.

That's the whole task. To share the locked file safely, send the password through a different channel than the document itself — a text or a call, not the same email.

Tips and common problems

• Store the password where you can find it. If you lose it, the document can't be recovered — there's no reset link or backup. A password manager is the safest place to keep it.
• Don't reuse a password you use elsewhere. A PDF you email could end up in many inboxes. Give it a unique password so a leak here doesn't expose your other accounts.
• Send the password separately. Putting the password in the same email as the attachment defeats the point. Use a different channel entirely.
• Already-encrypted files load fine. The tool can open PDFs that were previously protected so you can re-secure them with new settings.
• Need to remove a password instead? If you have a PDF you own and know the password for, the Unlock PDF tool takes the protection back off.
• Want to read more first? The complete PDF tools guide walks through the rest of the toolkit, and the password security guide covers building passwords that actually hold up.

FAQ

Does my PDF get uploaded anywhere? No. The whole thing runs in your browser using the PDF engine your browser already has. The file is processed on your device and the protected copy is generated locally — nothing is sent to a server, and you don't sign up for anything.

What's the difference between the user password and the owner password? The user password is what someone types to open and read the document. The owner password is an admin key that lets you change permissions without re-doing the file. You can set just the user password, or both.

Should I use 128-bit or 256-bit AES? Use 256-bit AES for anything genuinely sensitive — it's the stronger option and the default. Choose 128-bit only if you need to support an older reader that struggles with 256-bit.

Can I hide content instead of just locking the file? Locking controls who opens the document, but the content is still there once it's open. To permanently remove sensitive text or images, use the PDF redaction tool. To strip hidden author and software details, try the PDF metadata editor.

Working with PDFs a lot? You can also combine multiple PDFs into one before protecting them.