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 cannot be opened by anyone who does not have it. 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 without the password the content cannot be opened or read at all, by anyone. This is genuine, strong protection, and it is what keeps a sensitive document private.
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 truly must stay private, the password is what protects it, and you should only share that password with people you trust.
Is My File Safe?
Your files are handled securely, and we never store the password you set. Uploaded PDFs are deleted from our servers immediately after processing, whether it succeeds or fails. The locked result is stored under a random, unguessable name and stays available to download for up to two hours, then it is automatically and permanently deleted. All uploads and downloads use a secure HTTPS connection.
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.
