MISSOULA, Mont, -

If you want to search your neighborhood for sex offenders, there's a new app for that.

"The app populates the entire U.S.," creator Simon Gojcaj said. "You can put in the zip code anywhere in the U.S., and it will populate within the chosen range."

The new Criminal Tracker app came out just this week. It pinpoints the names and addresses of offenders up to 40 miles away. Gojcaj says he created the app because he was worried about his son and other kids he knows.

"We have a lot of children that are in our neighborhood, and I am concerned about their safety," he said.

Missoula nanny Kathy Kelly says tools like this one help her keep her kids safe.

"I really think that there's a lot of predators out there," she said. "And we need to be able to track them and see if they're in our area."

In Missoula County there are 300 registered sex offenders, 195 in Flathead County and 85 in Gallatin County.

"There might be none in my area," Kelly said. "But then if I do go somewhere else to watch kids in another area, I would want to know, to get on this and find them. So I think this is a great opportunity."

The app works on iPhones, iPads and iPod Touches and costs 99 cents. A similar Blackberry app called Vision 20/20 is available for $2.99.