The Fast Research Interface Library intends to provide a simple user interface to the KUKA Light-Weight Robot IV and hides all communication and set-up issues behind interface. It is only an interface and it does not contain any control functionalities. Without much installation efforts, access to different controller interfaces of the KUKA system is provided: Joint position controller, Cartesian impedance controller, and Joint position controller. The Fast Research Interface Library runs on a remote PC node with is connected to the KRC (KUKA Robot Controller) via an Ethernet connection. In intervals of 1 to 100 milliseconds, UDP packages are periodically sent from the KRC unit to the remote host. These packages contain a complete set of robot control and status data (e.g., joint positions, joint torques, drive FRIDriveTemperatures, etc.; cf. FRI User Documentation). Users become able to set-up own control architectures and/or application-specific controllers for the light-weight arm as it is often desired at research institutions. KRL files (to be installed on the KRC) are installed in ${PREFIX}/share/FRILibrary