Secure your documents with a password
When sharing sensitive information, it is essential to ensure that only authorized people can view your files. This Protect PDF tool allows you to easily add a password to any PDF document, encrypting its contents so that it cannot be opened without the correct credentials.
Because the tool processes everything locally in your web browser, your files are never uploaded to an external server. Whether you are securing financial records, legal contracts, medical documents, or personal letters, your data remains strictly on your device.
How to password protect PDF files
To lock a PDF, simply select your file and enter the password you want to use. You will be asked to confirm the password to ensure there are no typos. Once you click the protect button, the tool applies standard PDF encryption to scramble the document's contents.
When anyone tries to open the downloaded file in a PDF viewer—whether on a computer, phone, or tablet—they will be prompted to enter the password before the document renders. Without the password, the text, images, and metadata inside the file remain completely unreadable.
Managing PDF permissions
Beyond just requiring a password to open a file, you can also restrict what a user can do once the file is open. By opening the "Advanced settings" panel, you can configure specific PDF permissions:
- Allow printing: Uncheck this to prevent users from printing a hard copy of your document.
- Allow copying: Uncheck this to stop users from highlighting and copying text or extracting images to their clipboard.
- Allow modifying: Uncheck this to prevent users from editing the document, filling out forms, or adding annotations.
These restrictions are incredibly useful for sharing drafts, copyrighted material, or finalized contracts where you want the recipient to read the document but not alter or easily duplicate it.
User password vs. Owner password
When you encrypt a PDF, you are actually working with two different types of passwords:
The User Password (the main password) is what the reader must type in just to open and view the PDF.
The Owner Password is a master key used to manage the document's permissions. If you restrict printing or copying, you should set an owner password. If a user tries to change the document's security settings or bypass your restrictions in a PDF editor, they will be prompted for this owner password.
If you leave the owner password blank, the main user password will double as the owner password. If you only want to restrict copying but don't care who opens the file, you can leave the main password blank and only set an owner password.
Privacy and local processing
Most online PDF tools require you to upload your documents to a remote server, where they are processed and sent back to you. This creates a significant privacy risk, especially for the exact types of sensitive files you usually want to protect.
This tool works differently. It uses WebAssembly to run a powerful PDF manipulation engine directly inside your browser. When you add a password to a PDF, the encryption happens using your device's own processor. No data is transmitted over the internet, meaning your confidential documents are never exposed to third parties, server logs, or data breaches.
Best practices for locking PDFs
- Use a strong password: A password is only as secure as it is hard to guess. Use a mix of letters, numbers, and symbols, and avoid easily guessable words like names or dates.
- Keep a backup: PDF encryption is highly secure. If you lose or forget the password, neither this tool nor standard PDF software can recover the file for you. Always keep an unencrypted backup of your original document in a safe place.
- Prepare your file first: If you need to make your file smaller before sending it, use the Compress PDF tool prior to encrypting it. If you need to clean up hidden document properties, use Edit PDF Metadata first.
- Removing passwords: If you ever need to remove the password from a file you own, you can use our Unlock PDF tool, provided you still know the current password.