What is a qdf file and how do I open a qdf file?

The Quicken Data File is saved in the QDF format and is appended with the QDF extension, and is used by the Quicken personal finance software for Windows. These QDF files are generally classified as primary data files that contain accounts, transactions, portfolios, and balance information. These files are located in the following directory: C:Users[User Name]My DocumentsQuicken for Windows 7 users and C:Documents and Settings [User Name]My DocumentsQuicken for Windows XP users. Data files are named QDATA by default but the user can rename the data files.  Because these files contain very important information, it is important to back them up. They can be backed up by using USB drives, CDs, DVDs, or to a remote location. Another way of backing up data files is through online procedure such as Swapdrive. The Intuit Quicken software can be used in Microsoft Windows-based systems to access and view the content stored in these QDAT files.