Working with models often requires the ability to assert the compliance of a given model to a given set of constraints. Some tools are able to check OCL invariants on UML models. However, there are very few tools able to do the same for any metamodel. This is quite penalizing for the DSL (Domain Specific Language) approach to model engineering. In this paper we propose a metamodel-independent solution to this problem that uses ATL (Atlas Transformation Language). This solution has been implemented as an Eclipse-based plugin. Key words: Model Engineering, OCL, checking models, ATL