This deliverable describes the functionality and availability of the FABM Offline Simulator (fabmos) software package developed within NECCTON. This package provides a set of new biogeochemical/ecological model testbeds for the NECCTON interlinked modelling framework. The testbeds improve upon existing ones (box models, water column models) by better representing spatial variability and the impact of horizontal transport on biogeochemical/ecological variables. At the same time, the new testbeds maintain good computational performance, enabling a model year to be simulated in minutes to one hour on a single workstation. An example is included to demonstrate how an efficient testbed for an existing Copernicus Marine Service (CMEMS) Monitoring and Forecasting Centre (MFC) domain can be set up. We envisage the new fabmos package to be particularly useful for the development and parameterisation of new process descriptions within NECCTON.