GENFIT is an experiment-independent framework for track reconstruction for particle and nuclear physics. It consists of three modular components:

1. •Track fitting algorithms
   Currently, GENFIT contains a Kalman Filter and a Deterministic Annealing Filter. Other algorithm modules can be added easily.
   

2. •Track representations
   These modules hold the data of track track parameters and can perform extrapolations of these parameters. GENFIT is distributed with two well-tested track representations.
   Existing track extrapolation codes can be interfaced in a very straightforward way in this framework, using their native geometry and magnetic field interfaces.
   

3. •Reconstruction hits
   The hit dimensionality and the orientation of planar tracking detectors can be chosen freely. GENFIT is especially useful for tracking systems which include detectors which do not measure the passage of particles on predefined planes, like TPCs or wire-based drift chambers. The concept of so-called virtual detector planes provides a simple mechanism to use these detector hits in a transparent way without any geometrical simplifications.
   

GENFIT has been developed in the framework of the PANDA experiment at FAIR, Darmstadt, Germany. It is also used in the Belle-2, Fopi, and GEM-TPC experiments.

GENFIT is implemented in C++ and makes extensive use of object-oriented design. It is available here at sourceforge under the LGPL v3. There is a mailing list, which you can register for at https://lists.sourceforge.net/lists/listinfo/genfit-forum. A paper on GENFIT has been published in NIM A (preprint). Recent developments are described in another preprint.