Amazon wowed the tech world Sunday with a sneak peek at plans to one day deliver packages using unmanned aerial drones, but the e-tailer isn't the only one vying to fly the friendly skies.

The Verge reported that the world's largest parcel service is also keeping its eyes on the sky in the hopes of one day establishing its own fleet of aerial drones capable of delivering packages to customers.

According to sources familiar with the company's plans, United Parcel Service (UPS) has been actively "testing and evaluating" its own delivery drones, even before Amazon Prime Air made its television debut over the weekend.

"The commercial use of drones is an interesting technology and we'll continue to evaluate it. UPS invests more in technology than any other company in the delivery business, and we're always planning for the future," a UPS spokesman told The Verge, without directly confirming anything the carrier might have on the drawing board.

Infinity and beyond?

Robotics experts such as law professor Ryan Calo certainly aren't surprised by the ambitions of Amazon or UPS, despite regulatory hurdles that could take years to work out.

However, Calo remains skeptical UPS will adopt the kind of warehouse to residential front door delivery that made such a big impression in Amazon's demo video.

"But a company like UPS could use drones to bring packages quickly and cheaply from a major airport or city to pick-up centers in more remote locations, speeding up delivery for a lot of customers," Calo remarked.

FedEx has also expressed interest in shifting toward unmanned aircraft, but for now, shipping providers are left cooling their heels as the Federal Aviation Administration weighs rules for actually getting aerial drones into the air.