An Infinispan developer builds and manages scalable, high-performance, distributed in-memory data grid systems. They utilize Infinispan's capabilities for data storage, caching, and computing. They work on data replication and distribution across clusters for fault tolerance, load balancing and fast data access. They manage transactional data structures and perform complex queries. They also handle event-driven programming and continuous querying. They may also integrate Infinispan with other systems and monitor its performance. Their work is crucial for developing applications that require high availability, elastic scalability, and low latency.