Amazon today launched a new service that pays part-time drivers in exchange for delivering packages. The service, called Amazon Flex, launches today in Seattle, and will soon come to Manhattan, Chicago, and seven other US cities, according to its website.

As The Guardian reports, Amazon Flex appears to have taken its cue from Uber and other "gig economy"-based services. Drivers will be paid $18 to $25 an hour to deliver packages ordered with Amazon Prime Now, the company's one-hour delivery service, though the site suggests it will eventually expand to include other Amazon deliveries. To qualify, drivers must provide their own car, own an Android smartphone, and pass a background check. They can choose to work for two-, four-, or eight-hour shifts.

"Be your own boss."

Amazon says the service will allow drivers to earn extra money on their own schedule, echoing other sharing economy-based services. "Be your own boss," the site's tagline reads, "deliver when you want, as much as you want." But the growing industry has come under criticism and legal pressure. Uber has faced particularly fierce backlash over its refusal to treat its drivers as full-time employees, rather than independent contractors. The company is currently appealing a ruling in California that granted class-action status to a lawsuit brought by a group of drivers demanding stronger protections.

After Seattle, Amazon Flex will launch in Manhattan, Chicago, Baltimore, Miami, Dallas, Austin, Indianapolis, Atlanta, and Portland. The company has not set a timeline for its expansion.