PenProtect is described as 'The most comprehensive and secure solution to password-protect the files within your USB Flash Drive, Flash Memory, Pen Drive or USB Stick' and is a Disk Encryption tool in the security & privacy category. There are more than 50 alternatives to PenProtect for a variety of platforms, including Windows, Mac, Linux, Android and iPhone apps. The best PenProtect alternative is TrueCrypt, which is free. Other great apps like PenProtect are Axcrypt, Windows BitLocker, Encrypto and Secure Folder.