There are literally thousands of these types of companies, but Consumer Credit Counseling Services is the largest and most popular. InCharge.org is also well-reviewed.
Cargill is the largest private company in the United States
Gillette Company is the largest in the cutlery industry.
The largest vending company in the United States is the Canteen Company. Seaga however, is the largest worldwide vending company for snack, combo, vending and drinks.
As of 2014, the largest banking company in the United States is JP Morgan Chase and Company. The bank is headquartered in New York.
As of 2011 the largest title insurance company by premium volume in the United States is First American Title Insurance Company.
The company Health Plus's headquarters are located in Brooklyn, New York, United States of America. Health Plus is a nonprofit organization dedicated to quality health care.
UNCLE SAM
Comcast is the largest company so has the most customers. They are in most states.
"The largest rubbish removal company in the United States is 1-800-GOT-Junk. This is also their phone number and website, not only just their business name."
Incorporated in 1868, Deere and Company is one of the largest agricultural and industrial equipment manufacturers in the United States.
Government
The Secretary of State Office keeps a database of non-profit companies. In most cases it is online. The IRS.gov website also has a database on non-profits. You can also ask the company for their tax-exempt certificate.