FlagCX is a scalable and adaptive cross-chip communication library supported by the Beijing Academy of Artificial Intelligence (BAAI). It is part of the FlagAI-Open open-source initiative aimed at fostering an open-source ecosystem for AI technologies. FlagCX utilizes native collective communication libraries and comprehensively supports single-chip communication across different platforms. Supported communication backends include NCCL, IXCCL, and CNCL.