In-memory distributed state with delta conflict-free replicated data types (CRDTs) enable efficient management of distributed cache or configuration state on an Elixir cluster. Delta CRDTs are a type of conflict-free replicated data type that have the properties of no single source of truth, eventual consistency, and global convergence. They offer a way to replicate and merge state in a distributed environment without coordination between replicas. Operational transforms and delta state are two types of delta CRDTs used for different use cases. DeltaCrdt is an Elixir library implementing delta CRDTs, while Horde provides a distributed name registration and process supervisor on top of delta CRDTs. The Aviato.Agent module uses a CRDT to keep configuration data synchronized across a cluster of ephemeral cloud instances.