A FlatBuffers developer designs and implements high-performance, memory-efficient data serialization libraries. They create schemas defining data structures, convert data into FlatBuffers binary format for storage or transport, and decode it back into data structures. They also optimize data access without parsing or unpacking, reducing resource usage. Their work involves ensuring data integrity, versioning, and backward compatibility. They may also work on integrating FlatBuffers with other systems or languages, as FlatBuffers supports cross-platform development and a broad range of programming languages. Their role is critical in applications requiring speed and memory efficiency, like game development or real-time systems.