Forest scientists build models to study, understand and represent stand growth and dynamics. Ad hoc computer tools are often developed to implement these models, to test and to explore the consequences of the underlying hypotheses. Some teams have also developed more integrated tools, often based on a parameterizable growth model. The aim of this chapter is to present CAPSIS, a more generic forest simulator integrating various models, and to discuss the advantages for modellers and foresters of using such a shared forest-modelling platform for research, management and education. CAPSIS is free portable software, with a kernel providing the overall structure for simulations and generic data descriptions for stands, trees, soil, etc. These descriptions can be completed in modules - one for each model - which implement a proper data structure and specific evolution functions. A plug-in architecture allows the user to add tools for management, data exportation and representation, or connections with other software. At the present time, CAPSIS hosts six modules and two specific libraries. This shared forest-modelling platform has already shown many advantages: allowing modellers to re-use submodels and share specific tools, and providing to foresters and students a single easy-to-use software platform to compare different management strategies.