  We present the design of a flexible quantum-chemical method development
framework, which supports employing any type of basis function. This design has
been implemented in the light-weight program package molsturm, yielding a
basis-function-independent self-consistent field scheme. Versatile interfaces,
making use of open standards like python, mediate the integration of molsturm
with existing third-party packages. In this way both rapid extension of the
present set of methods for electronic structure calculations as well as adding
new basis function types can be readily achieved. This makes molsturm
well-suitable for testing novel approaches for discretising the electronic wave
function and allows comparing them to existing methods using the same software
stack. This is illustrated by two examples, an implementation of
coupled-cluster doubles as well as a gradient-free geometry optimisation, where
in both cases, an arbitrary basis functions could be used. molsturm is
open-source and can be obtained from https://molsturm.org.
