It's Halloween. You want to keep your trick-or-treaters safe and you want to avoid the homes of registered sex offenders.

There's an app for that.

Research Triangle Park-based Handstorm Inc.'s program, StaySafe, is one of several mobile applications that track registered sex offenders across the United States.

StaySafe, for the Apple iPhone, is just one app of its type. The P.O.M. Offender Locator is available for iPhone, BlackBerry and Android phones.

Both promise to track sex offenders and analyze risk level at a user's exact location.

The data is drawn from a national sex offender registry to find offenders by location, name and physical characteristics. The programs show photos and descriptions of each offender and what offenses they committed.

Parent Nancy Franks sees the utility of such a tool.

"You just want to make sure you're not getting candy from people you don't trust,” she said.

Most parents are aware that they can check a list of sex offenders on the Web site of the state Department of Justice. Mobile applications make that information available to people when they are away from the computer.

“A lot of times you think about that stuff when you're on the fly and you have to wait until you get home to look on the Web site,” parent Asa Fleming said. “(If) you have it on your BlackBerry, you can do it right then.”

Handstorm’s Dwayne Williams described how it works. “We look at where you are, look at a radius around you, ages of victims, gender of victims."

Asa Fleming said he would consider downloading an offender tracking app before his kids go hunting for sweets.

"Being on that list is something people need to know about, especially if you have children because you want to protect your family," he said.