To achieve the most general applicability of BasisOpt, it is important that the same procedures can be applied irrespective of the particular quantum chemical method, and beyond that, the choice of implementation of that method. For example, there have been an explosion of new local correlation methods available only in specific codes, yet the nature of the basis set and the optimization process should be the same. To this end, BasisOpt uses a skeleton Wrapper class, from which specific programs can be derived. Any given method can be exposed to the library in a standard fashion, and use of the high-level API requires no knowledge of how the program is operating.