What is a CFF file
CFF files are usually used by software to store citation information about the specific software. The information contained is written in plain text and thus human- as well as machine-readable. Contrary to other citation files, CFF files are used by developers and not by academics, scientists or scholars, since they reference software and help to correctly cite it.
The information inside the CFF file contains the version, a message, author, title, date of release and other information about the software it is used by.
Here's a small, but not exhaustive list of programs that can open CFF documents: