Walmart is testing yet another strategy to compete on Amazon's level in e-commerce.

The superstore chain already offers grocery delivery with a $9.99 fee at nearly 1,000 locations across the U.S., with free in-store pickup available at nearly 2,500 stores, but it is currently piloting a subscription service as well, Tech Crunch reports.

Delivery Unlimited, as the service is called, costs either $12.50 per month or $98 per year after a 15-day trial period, according to Walmart's website and its app, Walmart Grocery. The pilot program is currently running in Salt Lake City, Houston, Miami and Tampa, Tech Crunch reports. Prices are subject to change at this early stage.

On June 12, Target announced the expansion of its own same-day delivery service, powered by Shipt, the subscription-based app it acquired in 2017. Deliveries through the service are subject to a nearly $10 fee, just like non-subscription Walmart deliveries. Amazon offers grocery delivery from Whole Foods, which it calls Amazon Prime Now, to non-Amazon Prime members for about the same price.

Amazon pioneered subscription-based delivery with Amazon Prime, which now costs $119 per year but includes several other perks, such as access to its streaming video service. Unlike Amazon and Target, Walmart still contracts third-party delivery services such as Postmates and Doordash to fulfill its online grocery orders, according to Tech Crunch.

Walmart continues to pour investment into its e-commerce business, and its justification for doing so lies in its bottom line. It recently announced a $200M investment into optimizing its Canadian stores with its online business as signs emerged that its physical footprint may have peaked. Yet in the first quarter of this year, its e-commerce sale grew 37% and it beat projected earnings by 11 cents per share, Tech Crunch reports.