SUP is a native answer set solver that can be seen as a combination of computational ideas behind two answer set solvers: Cmodels and Smodels. SUP requires that the input be a grounded logic program as generated by the Lparse front-end. It supports choice rules and weight constraints, but does not allow for optimization statements.
SUP is currently at version 0.4 (as of 15 Dec 2014) and it is not clear if it is still under active development.