OFAC, is the agency within Treasury that enforces trade sanctions against various targeted foreign countries, groups, and individuals. Transactions with sanctioned countries or persons by U.S. persons or within the United States are prohibited. While there is no law requiring that people check these sanctions lists, it is illegal to do business with anyone on these sanctions lists.
The main sanctions lists are the Specially Designated Nationals (SDN) list and the Consolidated Sanctions list. Sanctions List Search is a free tool provided by OFAC to assist the public in complying with sanctions programs. This is for individual users that are looking for potential matches on OFAC's sanctions lists.
OFAC has configurations for automated systems and software programs. OFAC's SDN list is available in XML, fixed-field and delimited formats that can be imported into a variety of software programs. OFAC also publishes the SDN datain a comma separated values format (CSV). This format is recognized by Excel and other spreadsheet programs and can be imported into spreadsheet format by simply opening the file in your default spreadsheet application.
Of course, these lists must be updated with changes, so OFAC has an email subscription service that will notify you when there are updates to the sanctions list.