Amazon is attempting to take fast shipping to the next level by testing one-day deliveries with taxis.

Amazon is teaming up with Flywheel, a taxi-handling mobile app, to create their own faster delivery service.

"Amazon really created this market for faster and faster delivery, and if you're a retailer, you've got to do something to compete against that," Greg Bettinelli, a partner at Upfront Ventures, which is an investor in same-day delivery startup Deliv, tells Wall Street Journal. "But that also means Amazon can't stand still, they've got to keep innovating."

The taxi service is currently being tested in San Francisco and Los Angeles.

If the taxi service proves effective it could put Flywheel at a great advantage as it is competing with car services Uber and Lyft.

The taxi service, if successful, could also help Amazon contain shipping costs, which have been rising annually. This may also help the retailer who is competing with Google Express and eBay who offer one-day-deliveries.