Evan Malter, ZipCap’s founder and chief executive, considers the relationship aspect of ZipCap’s system just as important as the “cheap money” part. “We want people to see the impact they have on their local economy,” he said. “When a customer feels as though they have contributed to the success of a business, they have a greater bond to that business and are more compelled to visit.”

ZipCap’s unusual lending model, Mr. Malter said, emerged from his desire to fix flaws in other small-business financing options, particularly interest rates so high that he considers them predatory. It is also the result of trial-and-error experimentation.

Mr. Malter initially set out to create a very different venture: an equity crowdfunding site that would help business owners raise capital from their customers. But the more he learned about how neighborhood retailers operate, the less he liked that idea. Razor-thin margins leave little room for investor profit, he realized, and merchants’ accounting systems are often messy and ad hoc. “How a pizza shop owner is running the business is not something anyone can do due diligence on, much less the crowd,” he said.

So he started over, focusing on the issues that often prevent small-business owners from obtaining affordable loans: lack of collateral and low (or nonexistent) profitability. “By using customer loyalty as collateral and an asset, we’re creating an accounts receivable stream for the kinds of businesses that otherwise have none,” Mr. Malter said.

The question on which the entire model hinges, though, is how reliable customers’ spending pledges turn out to be. ZipCap has 10 Michigan businesses in various stages of a pilot program and is tracking their Inner Circle follow-through rates. At Beezy’s, five months in, 117 members — 90 percent of the group — are on pace to fulfill their pledges. Nine have already done so and renewed for another $475 commitment. One member dropped out, and 12 are falling short of their target.

To succeed, ZipCap will need to sell both merchants and investors on its loyalty capital concept and prove that it is an effective way to underwrite loans. Robert Foster, a veteran of the impact investing industry and a board member of the Social Venture Network, says the start-up is one he is keeping a close eye on.