Most state websites have a taxable entity search that provides the registered agent of each entity that does business in that state. In some states, this may be the State Comptroller's website. In others, this may be the website for the Department of Revenue or the state's Secretary of State.
A company's website or social media account may also provide owner information. If the business requires licensing or professional accreditation, the licensing or accrediting organization may provide information about its members. A state regulatory agency, state inspection database or city permitting office may provide useful information regarding ownership. The Better Business Bureau may provide valuable contact information.