If you are sharing a PDF that contains sensitive information, adding a password is a simple way to make sure only the right people can open it. This is useful for contracts you send to clients, financial documents you email to an accountant, or any file you want to keep private even if it ends up in the wrong inbox. You do not need Adobe Acrobat or any paid software to do it.

How to add a password to a PDF

1. Go to the Password Protect PDF tool.
2. Upload your PDF file.
3. Type in the password you want to set for the document.
4. Click Protect PDF.
5. Download your encrypted PDF.

Anyone who tries to open the file will be asked for the password before they can view any content. The encryption used is AES-256, which is the same standard used by banks and government agencies to protect sensitive data.

What does AES-256 encryption mean in practice

AES-256 is a very strong encryption standard. A PDF protected with AES-256 cannot be opened by brute force in any practical amount of time. As long as you choose a reasonably strong password, the content of your document is effectively inaccessible to anyone who does not have the password. Choosing a weak password like a name or a simple word still makes the file vulnerable to dictionary attacks, so use a mix of letters, numbers, and symbols for any document that is genuinely sensitive.

Is the file uploaded to a server

No. The entire encryption process runs in your browser using JavaScript. Your PDF file never leaves your device. No copy is stored on any server and nothing is logged. This means the tool is safe to use with documents containing personal information, financial data, legal agreements, or anything else that should stay private.

What if I need to remove a password later

If you have the current password and want to remove the protection from a PDF, use the PDF Unlock tool. Enter the existing password and download the unprotected version. This is useful when you want to share a document more freely after the sensitive period has passed.