PDF Password Adder

Real PDF Encryption, Right in Your Browser

This tool adds genuine password protection to a PDF. It encrypts the document with AES-256, the same standard used by desktop publishing software, and produces a file that prompts for a password whenever it is opened. The encryption is performed by qpdf, a battle tested open source PDF engine compiled to WebAssembly, running entirely on your device. Your document is never uploaded anywhere.

Many online PDF tools claim to add a password but only write a marker into the file. This tool does the real thing: the page content is encrypted, and without the password the file cannot be opened by any compliant reader, including Adobe Acrobat, Preview, Chrome, and Firefox.

Open Password and Owner Password Explained

A protected PDF can carry two passwords, and they do different jobs.

• Open password (user password): required to open and view the document at all. Recipients type this password before the first page appears.
• Owner password: unlocks full control. Opening the document with the owner password ignores the permission restrictions and allows printing, copying, and editing regardless of what is blocked. Leave it empty and it defaults to the open password.

A common setup is a firm open password that is shared with recipients, plus a different, private owner password that keeps full control with you. Because permission restrictions are enforced by the reader software, the owner password is what guarantees you can always lift them.

Permission Settings

• Allow printing: when off, the document can be viewed but not printed. Most readers obey this and grey out their print command.
• Allow copying text and images: when off, selecting and copying content is blocked, which protects wording and figures from being reused elsewhere.
• Allow editing: when off, modifications to the document are refused, keeping the file read only.

Permissions are respected by mainstream readers including Acrobat, Preview, and most mobile viewers. They are a strong deterrent and a useful control for business documents, but a determined user with the owner password can always change them, which is why the owner password should stay private.

How to Password Protect a PDF

1. Choose the PDF file. Files up to 100 MB are supported.
2. Type the open password that recipients will need. Add a different owner password if you want separate control.
3. Pick the encryption level. AES-256 is the default and recommended choice for every modern reader. AES-128 exists for compatibility with older enterprise software, and RC4 40-bit is a legacy option that should only be used when nothing else works.
4. Decide on printing, copying, and editing permissions.
5. Click Protect PDF, then download the encrypted copy. The original file on your device is untouched.

When to Password Protect a PDF

• Financial documents: bank statements, invoices, and tax records sent by email.
• Legal agreements: contracts and settlements that should only be read by the named parties.
• Medical records: health reports shared with a patient or a clinic.
• Business proposals: pricing, strategy, and internal reports that should not circulate freely.
• Personal documents: identity papers, rental agreements, and payslips.

Send the password through a different channel than the document itself. A password in the same email as the attachment offers very little protection, while a password sent by text message or told over the phone keeps the two factors separate.

Removing or Changing Protection Later

To take protection off a document you created, use the PDF Password Remover, which decrypts the file with the password and saves a clean copy. Before protecting a document, consider cleaning its hidden metadata with the PDF Metadata Editor and shrinking it with the PDF Compressor, since encryption tends to make files slightly larger. For protecting plain text rather than a PDF, the Encrypt Decrypt tool handles text with AES.

Privacy and Security Notes

The file, the passwords, and the encrypted output all stay on your device. The encryption engine runs in your browser tab, and no request ever carries your document or its password. That matters because a server based tool would see both the document and the password that protects it, which defeats the purpose. One honest limitation: JavaScript cannot guarantee that memory is wiped instantly, so close the tab after processing sensitive documents to release the memory.