With Free PDF Protector 4dots you can batch protect many PDF documents with passwords.

It is absolutely free, very easy to use and also multilingual.

You can set both a user password (used for opening the PDF documents) and an owner password (used for settings various permissions such as content copying, commenting,

printing, form field fill-in e.t.c.).

Whole folders with PDF documents and their subfolders can be selected and protected.

The PDF documents can be protected with 128 bits or 40 bits encryption passwords.

You can protect PDF documents simply with a right click in Windows Explorer since Free PDF Protector 4dots can be integrated into Windows Explorer.

Also, you can just drag and drop PDF documents to be protected to the main window of the application.

A text list file of PDF documents can be imported.

The application does NOT need Adobe Acrobat software installed.

With Free PDF Protector 4dots you can also batch set metadata of PDF documents such as author, subject, title, keywords, creation date e.t.c.

It can also be executed from the command line, which is useful for inclusion in scripts.

The application is translated into 38 languages.

To sum up, Free PDF Protector 4dots is the best free solution if you want to batch protect many PDF documents with a password without the need to have Adobe Acrobat software installed.