How to password-protect a PDF (and remove a password)

A password on a PDF means only people who know it can open the file. Because encryption is math, not a setting a viewer can politely ignore, it’s genuinely effective — which also means a lost password can’t be recovered.

Add a password

Protect PDF adds an open password using 256-bit AES, the same strength widely used for confidential documents. Choose a strong password, process the file, and share the encrypted copy. Anyone opening it will be prompted for the password first.

Store the password somewhere safe. There is no back door — if it’s lost, the file can’t be opened.

Remove a password

Unlock PDF removes the password and owner restrictions from a document you can already open — you supply the current password, and you get back an unrestricted copy. It does not crack or guess unknown passwords; that’s deliberate, so the tool can’t be used to bypass someone else’s protection.

Why do this in the browser?

Encryption and decryption run locally using qpdf compiled to WebAssembly. Your document and your password are never uploaded — nothing to intercept, log, or leak on a server.

Good habits

• Use a long, unique password — length matters more than symbols.
• Send the password through a different channel than the file.
• Remember a visible watermark or a flattened form is not the same as encryption.