The biogeochemical evaluation toolkit, BGC-val, is a model and grid independent python toolkit that has been built to evaluate marine biogeochemical models using a simple interface. Here, we present the ideas that motivated the development of the BGC-val software framework, introduce the code structure, and show some applications of the toolkit using model results from the Fifth Climate Model Intercomparison Project (CMIP5). <p><p> The key ideas that directed the toolkit design were model and grid independence, front loading analysis functions and regional masking, interuptabililty, and ease of use. We present each of these goals, why they were important and what we did to address them. We also present an outline of the code structure of the toolkit, illustrated with example plots produced by the toolkit. <p><p> After describing BGC-val, we use the toolkit to investigate the performance of the marine circulate and biogeochemical parts of the CMIP5 models, and highlight some predictions about the future state of the marine ecosystem under a business as usual CO<sub>2</sub> concentration scenario (RCP 8.5).