1. A method implemented on at least one computing device, each computing device having at least one processor, storage, and a communication platform connected to a network for providing identifiers to objects, the method comprising: categorizing received input data representing a plurality of objects into a plurality of entity categories; generating a first graph of entities using the plurality of entity categories; matching the first graph of entities with a second graph of entities; comparing object pairs, each object pair including a first object from the first graph of entities and a corresponding second object from the second graph of entities; and assigning identifiers to each object based on comparing the object pairs.