Alex Sifakis never raised this much money this fast.

The house flipper from Jacksonville, Florida, crowdfunded nine deals totaling more than $9 million through RealtyShares over the last two and a half years. A July deal for $1 million took him just 12 hours.

“Generally, raising money takes so much time,’’ said Sifakis, 33. “This offers so much flexibility and time savings. It’s so much better than going to family offices, banks or Wall Street firms.’’

House flippers and property developers are increasingly crowdfunding -- tapping the virtual wallets of anonymous internet backers on platforms such as RealtyShares, LendingHome, PeerStreet and Patch of Land. For riskier ventures, such as building new homes and buying, renovating and selling existing ones, they’re finding quick financing can be easier to get online than from banks. That’s contributed to an increase in home flipping. In the second quarter, 39,775 investors bought and sold at least one house, the most since 2007, according to ATTOM Data Solutions.

Marketplace Lenders

The crowdfunding sites are part of the multibillion-dollar ecosystem of marketplace lenders, like LendingClub Corp. and Prosper Marketplace Inc., that match users who need money with people who want to provide it for anything from debt consolidation to elective medical procedures.

That business hasn’t always run smoothly. LendingClub is going through a rough stretch after years of rapid growth. In May, its founder and chief executive officer resigned amid an internal probe into a botched loan sale, sending LendingClub’s shares tumbling.

So far, there have been few defaults in real estate crowdfunding deals. When they happen, the platforms say they’ll pay investors the proceeds from property sales.

The business has other potential pitfalls. When it comes to real estate, faster isn’t always better. Wall Street’s home-mortgage machine of the mid-2000s valued speed over accuracy, with disastrous results, though most crowdfunding sites cater to investors and not homebuyers. Also, clicking for capital can be exploited by fraudsters who may not be who they say they are, according to Sara Hanks, co-founder and CEO of CrowdCheck, which provides due-diligence services for online investors.

“We’ve seen some things where the entity that’s supposed to own the property doesn’t actually own it,’’ she said.