The easiest way to find out where a person works for free is to check for clues on social media websites. Try using LinkedIn or Facebook to search for the person by name.
LinkedIn, for example, is a social media site with a focus on a person's professional life. People often list previous and current employers, making LinkedIn an online version of the resume. Other social media sites, such as Facebook, often include information about employers on profile pages, and checking a person's Facebook friends can often give clues about his employer, especially if many friends list the same employer.
For a sum of money, private investigators also work to track down a person's place of employment, and paid background checks also often reveal this information.