gridxc is a library that receives the electron density values on the points of an arbitrary regular grid, and gives back the values of the XC potential and energy density on the same points in addition to the total XC energy. It is ready to use by any code using regular grids (e.g. plane-wave codes).
It encodes several local and semilocal density functionals (LDA and GGAs), and several non-local ones as defined for Van der Waals, including the original one by Dion et al (Phys. Rev. Lett. 2004) and its later variants from the same and other groups. It also includes the Van der Waals functional of Van Voorhis. All of them encoded using the efficient factorisation presented in G. Román and J.M. Soler, Phys. Rev. Lett. 2010 (the extension to the Van Voorhis functional is briefly described in F. Corsetti et al, J. Chem. Phys. 2013).