In order to offer flexibility in the generation of the reference data, BespokeFit makes extensive use of QCEngine , which is a program executor and IO standardizer, offering one unified interface to a plethora of QM, ML, MM and semi-empirical computation backends. Due to this unified interface and the plugin nature of QCEngine, new computational reference methods can be rapidly prototyped and used with Bespok-eFit, with no changes to the source code. For example, as more accurate and faster ML potentials become available in QCEngine, it will be trivial to make them available in BespokeFit for next-generation FF fitting.