The site attracted a potential new client named Jeff, a Missouri resident who last year pleaded guilty to wire fraud and, in a few weeks, will enter a federal prison camp in Kansas City for a one-year sentence. Jeff, who asked that his last name not be used because he did not want to widely publicize his conviction, said that he went looking for a consultant because, “I’m just interested in spending the least amount of time in prison as possible.”

He checked out a few other Web sites and corresponded with a competitor by e-mail, he said, but he was dismayed when the competitor responded with form-letter responses, including one that referred to helping Jeff and “his wife.” Jeff is not married.

Do the consultants make a difference?

They certainly can, according to people who work in the criminal justice system. A sharp consultant, they say, can help with complicated paperwork, in much the same way that a college consultant can help a family navigate complicated financial aid forms. That said, people can also do the work themselves.

Chris Burke, a spokesman for the Federal Bureau of Prisons, declined to comment on the industry.

Not all prison consultants are ex-cons. Some worked as prison guards or employ former prison officials. Others are lawyers. Their clean record is more of an asset than being able to brag about time behind bars, they say.

“You think a warden is going to change a decision based on advice from a former resident? That is just not going to happen,” said Joel Sickler, who runs Justice Advocacy Group and has been a prison consultant for 30 years and, before that, a prison guard. He said his unblemished past would go over better with prison officials when he’s trying to petition for, say, a client transfer.