To keep a lid on fraud, PeerStreet doesn’t originate loans like most of the other platforms. Instead, it created a secondary market. It buys hard-money, or high-interest-rate, loans made to real estate investors and spreads the risk among individuals, who purchase pieces of them online.

“If you’re originating and selling, you’re just trying to get as much volume as you can,’’ said Brett Crosby, a Google Inc. alum who co-created PeerStreet and is now chief operating officer. “In order to get more borrowers in the door, you start to drop underwriting guidelines.’’ PeerStreet got an early investment from Michael Burry, the hedge fund manager who was played by Christian Bale in the movie version of Michael Lewis’s 2011 book “The Big Short.”

Borrowing Rate

The ease of fundraising through these nontraditional lenders could be a warning sign, according to Erik Gordon, a law professor at the University of Michigan in Ann Arbor.

“Whenever you see a big difference between the terms on which you can raise money in one market versus another market, something is wrong in at least one of those markets,” Gordon said. “It usually is the market with the least-experienced players, and they usually end up wishing they hadn’t played.”

Sifakis said he’s borrowing money at an annual rate of 14 percent over two and a half years. He keeps all the profit he makes from selling homes, he said.

Crofton, Maryland-based Caruso Homes Inc. used RealtyShares to build new houses in Raleigh, North Carolina, and Washington, D.C. Wall Street isn’t as interested in financing single-family developments in smaller and medium-sized deals, making crowdfunding a better way to fund Caruso’s projects, said Chief Financial Officer Jack Haese.

Few Defaults

The companies are in the early stages. Patch of Land said it’s originated more than $180 million in loans, RealtyShares said it’s raised more than $200 million for real estate deals and PeerStreet said it’s funded more than $100 million. LendingHome won’t say how much it’s generated -- the company started crowdfunding only this year. Those totals are peanuts compared to platforms like Lending Club.

Jeff Bullian, a Boston-based consultant, has invested in about 30 deals on RealtyShares and in a handful of others on websites such as Patch of Land. So far, only one deal has gone bad, he said. In that instance, the platform, which Bullian declined to identify, went to bat for investors so everyone could get their money back along with a small return.