DataWeave is MuleSoft's data transformation and query language — used inside Mule 4 flows to transform, filter, aggregate, and map data between source and target formats. It supports JSON, XML, CSV, Java objects, flat files, HL7, and dozens of other formats. DataWeave quality is one of the most significant differentiators between a well-built MuleSoft integration and a poorly built one — inefficient DataWeave scripts that process data record-by-record instead of using streaming or batch operations are a common cause of performance issues in production. Our developers are expert DataWeave practitioners and every transformation is reviewed for performance before production deployment.