PDkefProtect & Unlock PDFOn-device
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Unlock or Protect a PDF Free

Add a password to protect a PDF, or remove one you already know - the tool detects which you need. Free, open source, and your file stays on your device.

Drop PDF here to unlock

Private. Files never leave your device.

Open a different file?

This closes the current PDF. It stays in your recent files with everything you've done, so you can come back to it from the home page.

Clear all files?

This empties the list and the order you put it in. Nothing is removed from your device.

Turn on airplane mode and give it a try. It still works.

How it works

How to unlock or password-protect a PDF online for free

Add or remove a PDF password, right in your browser. No upload, no server. Your file and its password never leave your device.

  1. Upload your PDF. Select or drag-and-drop the file you want to protect or unlock.
  2. Enter a password. Type the current password to remove it, or set a new one to add protection.
  3. Save and download. Click the button and save a copy with the password added or removed.

Free for everyone

Protect or unlock as many PDFs as you like, with no watermark or usage caps. Because the file and its password are processed on your device, nothing is ever uploaded.

It's open source under the MIT license, so anyone can read the code, fork it on GitHub, or share it. Simple PDF tools should be free for everyone.

Got questions?

Frequently asked questions

Is my PDF or its password uploaded anywhere?

No. Nothing is uploaded. The password and the file are processed on your device, in your browser, whether you are adding or removing protection, and neither leaves it. There is no processing server. For offline use, install PDkef and let its required assets load while connected.

How do I add a password to a PDF?

Upload a PDF that is not already encrypted and the tool switches to protect mode automatically. Set the password you want, click Protect PDF, and download a copy that requires that password to open.

Do I need to know the PDF password to unlock it?

Yes. To remove a password you must already know it - this tool does not crack, guess, or recover unknown passwords. To add a password, you choose it yourself.

What if I enter the wrong password?

You will see an error and can try again. No file data is sent anywhere when this happens, so there is no risk in retrying.

Is there a limit on file size?

No artificial limit. Both protecting and unlocking run entirely on your device, so the only constraint is your device's available memory.

Same suite

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Every one of these runs on your device, free, with nothing uploaded.