sci qfits is a stand-alone library written in C to interact with files complying with the FITS format. It is fast and portable over any kind of POSIX-compliant platform. Rather than going through the FITS format specification and trying to implement some support for everything that is described there, this library was built day after day upon request. This guarantees that all the functions you will find in the library have been written for some purpose in the VLT pipeline context, and all of them are used daily in a production environment.