An Application Program Interface (API) manages synchronization and replication of master data of a system with different consumers. An API engine is configured to receive from the third party, a query including content information and date-relevant information including a start date, an end date, and a date of last synchronization. The API engine processes the query to access the database and produce a query result replicating only data changes affecting that period or a previous time. The consumer thus specifies the time period in which to consider changes to the stored database data, and the API calculates the delta according to that period. In this manner complex, time-dependent delta calculation and filtering logic can be implemented in the API without requiring substantial logic or additional data persistence in middleware. Particular embodiments may facilitate efficient synchronized replication of employment data to outside (e.g., payroll, benefits) providers.