Abstract: An asynchronous data validation mechanism integrated into a user interface by a binding engine is provided. Application object properties are bound to user interface data fields. The asynchronous validation mechanism communicates with a validator and with the object properties. Data input to a single field can be flagged with multiple validation errors. Multiple validation errors can also be associated to the object overall rather than being associated with particular properties of the object. Inconsistency between inputs to different data fields can result in a cross-property validation error. A single flag indicates whether the business object has any validation errors. Different validation errors may have different visualization types, and the business object may have validation errors of different data types, rather than being limited to strings.