Maria is a powerful tool designed to aid engineers in modelling and solving concurrency related problems in parallel and distributed computing systems. . Maria finds deadlocks and violations against safety or liveness requirements by exploring all states that can be reached from the initial state of a system. The tool manages tens or hundreds of millions of reachable states and enabled actions. . The expressive power of Maria's formalism is close to high-level programming languages, thanks to its rich data type system and powerful algebraic operations.