The free Lock PDF tool protects a document with a password using 256-bit AES encryption, the strongest encryption the PDF format supports. Upload your file, set a password, and download a locked PDF that asks for that password before it opens. It is free, adds no watermark, and needs no account.
You can also set optional restrictions on printing, copying, and editing. It is worth understanding the difference between the two protections, because they are not equally strong, and being honest about that matters more than a bold marketing line.
How to Lock a PDF
- Upload your PDF. Select the file or drag it onto the upload area.
- Set a password. Enter the password that will be required to open the document.
- Choose restrictions (optional). Tick the boxes to prevent printing, copying, or editing if you want to.
- Lock and download. The tool encrypts the file and you download the protected PDF.
Password Encryption vs Permission Restrictions
The open password is the real lock. Your PDF is encrypted with 256-bit AES, so the content cannot be opened or read without the password. This is genuine, strong protection, but it is only as strong as the password you choose, so avoid short or common ones.
The printing, copying, and editing restrictions are a weaker, separate layer. They are permission flags that well-behaved PDF viewers agree to honor, but they can be removed by anyone who has the open password and the right software, including our own unlock tool. Treat them as a way to discourage casual printing or copying, not as an absolute barrier. If a document needs real protection, the password is what provides it, and you should only share that password with people you trust.
What Happens to My File?
Your PDF is uploaded to our server and locked there. The upload is deleted when processing ends, whether it succeeds or fails. The locked result is stored in a folder with a random name and stays available to download for about two hours, then it is automatically deleted. Uploads and downloads go over HTTPS. We do not offer password recovery, so keep a copy of the password yourself.
When to Lock a PDF
- Sending sensitive documents. Protect a contract, financial statement, or medical record before emailing it.
- Sharing confidential work. Require a password on internal reports or unreleased material.
- Protecting personal files. Lock documents that contain personal or financial details.
- Controlling a shared file. Discourage printing or copying of a document you distribute.
Related PDF Tools
Need to remove protection you set? Unlock a PDF. To truly remove sensitive content rather than hide it, use Redact PDF. You can also add a watermark.
