FlexCRFs is a conditional random field toolkit for segmenting and labeling sequence data written in C/C++ using STL library. It was implemented based on the theoretic model presented in (Lafferty et al. 2001) and (Sha and Pereira 2003). The toolkit uses L-BFGS (Liu and Nocedal 1989) - an advanced convex optimization procedure - to train CRF models. FlexCRFs was designed to deal with hundreds of th