As he visited personal-finance sites, Shergill says he found useful information, but much of it was too broad in scope and aimed at "the average person" rather than tailored to individuals.

"What they didn't do is give any hard data on how you should be spending," he says. "How are some people just like you, in age, geography, household status and income spending a lot less in certain categories?"

Building a site with a wealth of information and data was made easier by Shergill's relationship with Citigroup.

"We would need to get data on at least 10 million people to actually drill down" to useful comparisons, he says. "Every time you swipe a debit card or credit card, that is data that is generated."

-- Reported by Joe Mont in Boston.

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