Protect PDF with a Password
Add a password to any PDF with AES-256 encryption and choose whether people can print, copy or edit it. Free, and your file and password stay on your device.
Your files are processed in your own browser and are never uploaded to our server.
How to password protect a PDF
- Choose or drop the PDF you want to lock.
- Type a password of at least 6 characters and type it again to confirm. A mix of upper and lower case letters, numbers and a symbol makes it strong.
- Untick anything you do not want people to do with the file, such as printing or copying text. Leave everything ticked if you only want a password to open it.
- Click Protect PDF and download the locked copy. Your original file is not changed.
What the protection does
| Setting | What happens |
|---|---|
| Password to open | Every PDF reader (Adobe Acrobat, Chrome, Edge, Safari, phone apps) asks for the password before showing any page. |
| AES-256 encryption | The pages, text and images are encrypted with AES-256, the strongest standard PDF encryption. Choose AES-128 only if a very old reader cannot open the file. |
| Print / copy / edit limits | If you untick an option, the file also gets a separate random owner password that blocks it. Adobe Reader and most browsers respect these limits, but some tools ignore them, so do not rely on them for secrets. The open password is the real protection. |
Tips for a safe password
- Use at least 8 to 12 characters. Short or common passwords such as 123456 or a date of birth can be guessed by password-cracking software.
- Do not send the password in the same email or chat as the PDF. Share it by phone or a different app.
- Write the password down somewhere safe. There is no “forgot password” for a PDF: without it, the file cannot be opened by anyone.
- A digital signature on the PDF stops being valid when you add a password. Protect the file before it is signed, or keep the signed original.
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Frequently asked questions
How do I put a password on a PDF for free?
Add the PDF above, type and repeat a password, and click Protect PDF. Download the new file. It now asks for the password whenever someone opens it. There is no sign-up, watermark or limit.
Is my PDF uploaded to your server?
No. The file is encrypted by JavaScript inside your own browser, so the PDF and the password never leave your device. That makes the tool suitable for bank statements, salary slips, ITR and GST documents and agreements.
Which encryption is used?
AES-256 by default, the encryption used by Adobe Acrobat for its highest security level. AES-128 is offered for older software. Weak RC4 encryption is not used.
Can I protect a PDF on my phone?
Yes. It works in Chrome, Safari and other modern browsers on Android and iPhone. The protected PDF downloads to your phone like any other file.
What if I forget the password?
It cannot be recovered or reset, by you or by ToolsRiver, because we never see it. Keep the original unprotected file or note the password somewhere safe.
Can I add a password to a PDF that already has one?
Remove the old password first with Unlock PDF, then protect the unlocked copy with the new password.
Will the protected PDF open in Adobe Reader and Chrome?
Yes. AES-256 is supported by Adobe Acrobat and Reader (version 9 and later), Chrome, Edge, Firefox, Safari, Foxit and the PDF apps on Android and iPhone.
Last reviewed: November 2026. Tested with PDFs from Word, LibreOffice and scanners, AES-256 and AES-128, and with print and copy limits, checked in a separate PDF program.