Splitting dinner checks can cause a splitting headache, even when the diners are a math-oriented data miner, a database security specialist and an expert in networked games.
Fed up with haggling over shared debts, Carnegie Mellon University computer science graduate students Shashank Pandit, Amit Manjhi and Ashwin Bharambe three years ago created Buxfer, short for "bucks transfer." The social-networking site with a personal-finance focus allows users to form groups of friends or housemates and track who owes what for utility bills, dinner tabs, day trips and other shared expenses.
Instead of fretting over how every dinner bill should be split, Bharambe, Manjhi and Pandit realized that they could track their collective expenses over longer periods of time. For example, one housemate could pay for dinner and a movie for everyone, earning credits in his Buxfer group and therefore paying less than his roomies on the next month's utility bills.
Buxfer quickly became popular with its creators' friends and colleagues, many of them college students or young professionals on a tight budget.
In September, Pandit, Manjhi and Bharambe launched a Web site offering Buxfer to the public at no cost.
Since then, Buxfer has grown to about 3,000 users who have completed transactions worth more than $875,000, said Pandit, 24. Most users are university students, some from as far away as India and Australia, he said. The site allows users to set the default currency to dollars, Euros, pounds, yen or rupees. But it doesn't offer a conversion feature.
News of the site has spread largely by word of mouth, on blogs and by flyers posted at universities, Pandit said.
Kedar Dhamdhere, 28, a software engineer at Google Inc., said he uses Buxfer almost every day. Before he relied on scraps of paper and memory, which wasn't very reliable.
"Instead of doing all the calculations, I just enter the information in Buxfer and that's it," he said.
Dhamdhere has created three groups in his Buxfer account, two for separate groups of friends and another for a roommate he shares expenses with.
Buxfer automatically e-mails Dhamdhere and other users in his groups about new transactions and payments. And when he logs into Buxfer, icons on the home page show him how much he owes or is owed.
The program begs for additional features, said Michael Shamos, a computer science professor at Carnegie Mellon who also specializes in e-commerce.
"Just keeping track of debts is nice," he said. "But wouldn't it be nice if you could also pay them. Right now there isn't any facility for doing that."
Buxfer's creators acknowledged that many users have asked for online debt settlement. They said they're exploring options such as working with an online payment service like eBay Inc.'s PayPal or a bank. Pandit said he and his friends are determined to keep access to the site free.
The site might find a niche audience among some students, accountants, techies on a tight budget and "math-oriented people with a high sense of personal justice," said Dennis Galletta, a professor of information systems at the University of Pittsburgh's Katz Graduate School of Business.
Still, the basic idea behind Buxfer may turn many people off: Unlike sites such as Friendster, Facebook and News Corp.'s MySpace, Buxfer "hinders the social," Galletta said. "It reminds people that they owe you money. Most people don't care so much and they'll pay for things. Okay, so they pay one extra time. But who cares if you're $6 over or $10 under?"