... and offloads. These include RDMA (InfiniBand and RoCE), TCP, GPUs, shared Memory, and network atomic operations. UCX facilitates rapid development by providing a high-level API, masking the low-level details, while maintaining high-performance and scalability. UCX implements best practices for transfer of messages of all sizes, based on accumulated experience gained from applications running on the world’s largest datacenters and supercomputers.