Let's zoom out of the reactive front-end story to see the big picture. How data and events propagate between clients and servers? What if clients are mobile and connections are intermittent? What about offline work? Can we cache our data? What if we need to act in real time? Welcome to the world of distributed mutable state, also known as ""hell"". Way too often, existing methods pretend that we act in a single point, at a single moment of time, alone (think ACID). One approach to truly asynchronous thinking is the math apparatus known as CRDT (Commutative/Convergent Replicated Data Types). I will tell how CRDT can be practically used to resolve some of the challenges mentioned.