Walmart Inc. (WMT) is set to expand its online grocery delivery service to 100 cities by the end of year in a bid to fight off rising competition from rivals, Amazon.com Inc. (AMZN), Kroger Co. (KR) and Target Corp. (TGT).

In a statement, the Bentonville, Arkansas-based retail giant claimed that the expansion of its same-day home delivery service from six markets to 100 metropolitan areas will enable it to serve more than 40 percent of U.S. households. Walmart will use its own personal shoppers to pack orders placed online and a “crowd-sourced delivery service” to transport these same groceries to customer doorsteps. According to CNBC, Uber will continue to be one of the retailer’s delivery partners.

Walmart also plans to increase the number of its stores offering curbside grocery pickups by 1,000 to 2,200 by year-end. The service uses personal shoppers to select items and then take them to shoppers’ cars parked outside.

“We’re saving customers time by leveraging new technology, and connecting all the parts of our business into a single seamless shopping experience: great stores, easy pickup, fast delivery, and apps and websites that are simple to use,” said Greg Foran, president and CEO, Walmart U.S. “We’re serving our customers in ways that no one else can. Using our size and scale, we’re bringing the best of Walmart to customers across the country.”

Walmart’s costly plans to bulk up its delivery services comes amid an onslaught of competition in the online grocery sector. Amazon recently added two cities to its new Prime grocery delivery service, while Kroger and Target have been busy teaming up with third-party delivery partners, including Instacart, Deliv and Shipt. (See also: Why Amazon Is Spending $1B on a Doorbell Company.)

Unlike some of its competitors, Walmart’s doesn’t require customers to pay a subscription for home deliveries. However, shoppers must pay a $9.95 fee and place a $30 minimum order to qualify for the service.