Welcome, Guesty: A Company That Helps Manage and Maintain Airbnb PropertiesThe company is a middle-man you never knew you needed.

The promise of the sharing economy—in which under-utilized assets such as private homes and cars are made available to rent—is creating entire ecosystems of new business to support it. That's what twin brothers Amiad and Koby Soto had in mind when they launchedGuestyin 2014. Their focus? Helping Airbnb's hundreds of thousands of hosts around the world manage and rent their properties to the site's 17 million guests.

Their idea was born of frustration. The Sotos, who lived in Tel Aviv, Israel, at the time, found themselves scrambling to tend to guest-related issues when employing Airbnb to rent out their own apartments. When Koby's idyllic vacation on a Spanish beach was interrupted by e-mails from a pesky Airbnb-booked guest, he became annoyed. But Koby, who writes code and had participated in three Israeli startups, and Amiad, whose background is in sales, also saw opportunity.