Most Social Security numbers of living people are masked for privacy purposes, but companies such as Accurint, TLO, KnowX and LocatePlus do maintain private databases of name-linked Social Security numbers. Social Security numbers can also legally be found on public domain court records, death records and professional licensing records.
The Social Security number of a deceased person can be located in the Social Security Death Index on some ancestry websites. The U.S. government's Social Security Number Verification Service can be used to verify that a number and name match the government's records. This service is often used by employers to screen new employees and avoid incorrect information on tax documents such as the W-2.