Model-driven engineering (MDE) is widely used nowadays in the design of embedded systems,
such as in the automotive, avionics or telecommunication domains. Behind the scenes, design and verification tools frequently exploit advanced model query and transformation techniques to support various rich tool features. The rapid increase in the size and complexity of system models has drawn significant attention to incremental model query and transformation approaches, which enable fast and incremental reactions to model changes caused by systems engineers or automated design steps. In this presentation, we overview two open source Eclipse projects, IncQuery and VIATRA, which have been actively used as a basis for developing various academic and industrial tools for critical systems.