you can try to use the shift operation to map the nested JSON structure to the desired flat structure while iterating over the SalesArea list. Below is the JOLT spec for your use case: [ { "operation": "shift", "spec": { "CustomerMaster": { "Rootnode": { "KUNNR": "[&1].KUNNR", "NAME1": "[&1].NAME1", "LAND1": "[&1].LAND1", "Indicator": "[&1].Indicator", "TimeStamp": "[&1].TimeStamp", "SalesArea": { "": { "VKORG": "[&2].[&1].VKORG", "VTWEG": "[&2].[&1].VTWEG", "SPART": "[&2].[&1].SPART" } } } } } }, { "operation": "shift", "spec": { "": { "*": "" } } } ]