1. A computer-implemented method, comprising: capturing an image of a document using a camera of a mobile device; performing optical character recognition (OCR) on the image of the document; extracting an identifier of the document from the image based at least in part on the OCR; comparing the identifier with content from one or more reference data sources, wherein the content from the one or more reference data sources comprises global address information; and wherein the content from the one or more reference data sources is derived from geographic information organized in one or more of a proprietary address database and an open source address database; and wherein deriving the content from the geographic information comprises: obtaining the geographic information from one or more of the proprietary address database and an open source address database; and parsing the geographic information according to a set of predefined heuristic rules, wherein the set of predefined heuristic rules are configured to normalize the global address information obtained from the one or more sources according to a single convention for representing address information; and determining whether the identifier is valid based at least in part on the comparison.
9. The method as recited in claim 1 , comprising determining a locality associated with the identifier; and wherein the set of predefined heuristic rules are selected based on the locality determined to be associated with the extracted identifier.