The business plan of Varsity Monitor is simple. Major universities like North Carolina, Nebraska and Oklahoma pay $7,000 to $10,000 a year and Varsity Monitor keeps an online eye on their athletes.

Among the services the company and others like it provide is a computer application that searches social media sites that athletes frequent, looking for obscenities, offensive commentary or words like “free,” which could indicate that a player has accepted a gift in violation of N.C.A.A. rules.

Yet some express concerns about the service.

“I think it’s violating the Constitution to have someone give up their password or user name,” said Ronald N. Young, a Maryland state senator who has sponsored a bill that would make it harder for universities to monitor their athletes online. “It’s like reading their mail or listening to their phone calls.”