Computer files with a name that ends in “.CDF” are called “Content Definition Files.” These files are used by one of two programs that only work with the Windows operating system. If you want to open a .CDF file that you’ve found on your computer or downloaded from the Internet, you’re going to need to make sure that you have either ECMG Reader or ECMG Explorer installed on your machine. Writer Bio

How to Open CDFs  5 Steps  - 23