Get ready for the online grocery wars.

Instacart, the San Francisco-based grocery delivery company founded by former Amazon engineer Apoorva Mehta, just opened for business in Seattle.

Interested users inside Seattle proper can order groceries from QFC and Costco through Instacart’s mobile or Web apps, and get everything from fresh lettuce to cartons of milk delivered within an hour.

Instacart is a bit different from Amazon Fresh — whose lime green delivery trucks have become commonplace on the streets of Seattle over the past seven years.

It relies on a team of personal shoppers, armed with smartphone apps, to go out and purchase food from local stores and then deliver it to users.

Users order groceries from their neighborhood store, as well as get products from Costco without holding a membership. That’s a sharp contrast to Amazon’s model of working with its own warehouses and truck fleets, and it allows Instacart to offer on-demand delivery.

The company is only offering delivery in Seattle proper, though its regional roll-outs start small and expand later. The company has to train personal shoppers, as well as ensure that there are enough stores in the right places in order to provide rapid delivery.

People interested in figuring out the price difference between Instacart and their local bodega might have a tough time, though. Susie Sun, a City Launcher for Instacart in charge of Seattle, declined to provide specifics about the company’s pricing.

“We work with different stores in different ways, so as a whole, our prices are our own,” she told GeekWire. “Sometimes it’s similar, sometimes it’s higher, sometimes it’s lower.”

The company sees a lot of potential in this expansion, and not just because of the competition with Amazon Fresh.

Sun told GeekWire that Seattle was among its most requested cities since the company launched.

In a press release, Mehta said that he believes Seattle’s young, tech-savvy population, combined with its rainy climate, will be a profitable mix for the company.

The news comes two weeks after the company posted a job listing for a pair of City Managers to work on the company’s operations in the Emerald City. Seattle is Instacart’s ninth city, joining New York, Los Angeles, Chicago, San Francisco, and Washington, D.C.

Instacart is pulling out all the stops to try and ensure its launch in Seattle will be successful. For the first time in the company’s history, Seattleites who place an order with Instacart from now until May 18 will get a month of free shipping.

In addition, three people who place an order and then tweet about the service with “#InstacartSEA” will receive a free year of delivery. The moves seem like a clear effort to push Amazon Fresh customers to try out the service.

After the promotional period, standard delivery within two hours of ordering costs $3.99 per order. Users interested in one-hour delivery will have to pay $14.99 an order.

For people who are interested in free delivery but don’t win the sweepstakes, they can purchase an Instacart Express subscription for $99 a year, which will give them free delivery within two hours of their order.