In order to find out if a company exists, the name of the company in question and the state it is in must be known. Search for a Certificate of Good Standing on that state's Secretary of State website.
In order for companies, such as limited partnerships, corporations, corporate non-profits and other incorporated entities, to engage in business transactions within a state, they must first file for a Certificate of Good Standing with that state's Secretary of State. A Certificate of Good Standing is often referred to as a Certificate of Existence or a Certificate of Authorization, although some states, like Texas, have different meanings for the two. In such cases, search for a Certificate of Existence instead.