Boxed.com's Smart Stock Up.

Call it the battle of the reorder buttons, or race for replenishment.

Boxed.com, the latest e-commerce site to launch a reorder feature, on Wednesday will introduce Smart Stock Up, which applies machine learning to customer data to predict when shoppers are running low on products, and makes reordering them easy.

Last week, walmart.com rolled out an Easy Reorder button, which has an automatic list-builder that keeps track of products consumers buy both online and in stores, and lets them view and repurchase items quickly and easily.

Fulfillment is seen as a big opportunity, with Easy Reorder contributing to Wal-Mart’s 63 percent increase in online sales in the first quarter. Easy Reorder is the retailer’s answer to Amazon‘s Dash,Wi-Fi-connected buttons introduced in 2015 for Prime members for a limited number of branded products. Amazon has since increased the number of buttons to about 300.

Boxed.com, which sells in bulk categories such as grocery, bath and body, baby and pets, is a fraction of the size of walmart.com and Amazon. However, it’s growing quickly. The site posted $100 million in revenue in 2016, and has raised more than $160 million in venture capital.

“We expect that Smart StockUp and Concierge will further fuel the company’s growth, making it easier than ever for our customers to shop, stock up and save,” said Will Fong, chief technology officer at Boxed.com, adding that the site’s average order size is $100, and about 10 items.

Founder and chief executive officer Chieh Huang grabbed headlines in 2015 when he announced a college tuition fund for employees’ kids. The following year, he offered to pay $20,000 toward staffers’ weddings.

Smart Stock Up, which was tested by about 25 percent of Boxed.com consumers as part of a pilot program, frees shoppers to engage with the site immediately, without running through a mental checklist for products that need replenishing.

Boxed.com is also introducing Concierge, an autonomous shopping concept that again, uses machine learning to predict when a consumer is running low on something, and preemptively fills and ships the order without any engagement from the customer.

“Concierge is hands-free shopping,” said Fong. “The order just shows up when they need it. Boxed.com refills products you’re running low on and sends you things we think you might like.”

If customers don’t want the extra items, Boxed.com has free returns. Fong pointed out that during Concierge’s trial period, there were no returns from customers. “In terms of add-on items, Boxed.com personalizes every order to meet the needs of customers,” he said. “We send them ‘discovery’ items based on their order history.

“The goal is to take the thinking out of shopping. That’s the future of e-commerce.”