We present CommunityWatch, an open-source system that enables timely and accurate detection of BGP routing anomalies. CommunityWatch leverages meta-data encoded by AS operators on their advertised routes through the BGP Communities attribute. The BGP Communities values lack standardized semantics, offering the flexibility to attach a wide range of information, including AS relationships, location data, and route redistribution policies. Therefore, parsing and correlating Community values and their dynamics enables the detection and tracking of a variety of routing anomalies. We exhibit the efficacy of CommunityWatch through the detection of three different types of anomalies: infrastructure outages, route leaks, and traffic blackholing.