Almost every New Yorker has had that moment: finding oneself on a strange block in an unfamiliar neighborhood late in the evening and wondering, "am I in a bad situation?"

Well, now there's an app to answer that question.

SketchFactor, the brainchild of co-founders Allison McGuire and Daniel Herrington, is a Manhattan-based navigation app that crowdsources user experiences along with publicly available data to rate the relative "sketchiness" of certain areas in major cities. The app will launch on iTunes on Friday, capping off a big week for the startup, which was named as a finalist in NYC BigApps, a city-sponsored competition that promotes technologies designed to improve quality of life issues in New York City and government transparency.

According to Ms. McGuire, a Los Angeles native who lives in the West Village, the impetus behind SketchFactor was her experience as a young woman navigating the streets of Washington, D.C., where she worked at a nonprofit.

"How can we take large amounts of data and crowdsource opinions on certain areas?" she wondered to herself. "I brought that idea to a Lean Startup event in D.C., it got a huge reception and suddenly I was on my way."

After meeting Mr. Herrington, an electrical engineer who was taken with the SketchFactor idea, the two quit their Washington D.C.-based jobs and decamped to New York City with funding from family and friends.

As one of the finalists in the BigApps competition, SketchFactor is poised to receive more attention when it launches. The founders are also bracing for potential complications from an app that asks anonymous users to judge a neighborhood's sketchiness. After all, fear can be subjective. And the site could be vulnerable to criticisms regarding the degree to which race is used to profile a neighborhood.

"We understand that people will see this issue," Ms. McGuire said. "And even though Dan and I are admittedly both young, white people, the app is not built for us as young, white people. As far as we're concerned, racial profiling is 'sketchy' and we are trying to empower users to report incidents of racism against them and define their own experience of the streets."

Ms. McGuire and Mr. Herrington are confident that the app has widespread appeal to cities nationwide, especially beyond the New York market.

"I live in New York now," said Ms. McGuire with a laugh. "So almost nothing's sketchy to me anymore."