A system and method for on-demand data cleansing is disclosed. The system includes a processor and a volatile memory including a data object having a plurality of data fields, each field having a tag and a value. The system also includes a cleansing module stored in the volatile memory and executed by the processor. The cleansing module includes a library having a plurality of tag-operation pairs. The cleansing module is configured to receive a pointer locating the data object within volatile memory, and further configured to, for each data field, look up the tag of the data field among the library tags, and execute the operation paired with the matching library tag on the value of the field, modifying the value of the data field while it is stored in volatile memory. The cleansing module is configured to execute the operation in near real-time, and at runtime.