Wal-Mart will test out an unlimited free shipping service that is very similar to Amazon Prime. The service would allow Wal-Mart customers to order more than 1 million different products on the Wal-Mart website and have them shipped for free within three days, Fox Business reports.

Wal-Mart's free unlimited shipping service will cost $50 per year. Wal-Mart will test the program this summer to select customers by invitation only.

Amazon Prime is Amazon's free two-day shipping service that allows customers to order items with no minimums and have them shipped for free within two days. It costs $99 per year and comes with streaming videos and music.

Wal-Mart's plans were first reported by technology industry publication The Information.

Wal-Mart is trying to increase its online business. In 2014, online sales increased 22 percent worldwide, but online sales only equaled $12.2 billion of Wal-Mart's $485.7 billion in total revenue.

Fifty dollars might be too much for Wal-Mart's core customers, those who are low-income shoppers and bargain hunters, David Strasser, a retail analyst at Janney Montgomery Scott, said.

"$50 is a pretty healthy sum of money for Walmart customers," Strasser said.

Wal-Mart might be looking at the higher-end shoppers at its stores and trying to get them to shop more frequently, Strasser said.

Currently, Wal-Mart only offers free shipping on orders that are $50 or more. Customers can purchase items online and pick them up in stores for free if they choose, according to USAToday.

Amazon said that Prime memberships increased by 50 percent in the U.S. last year.

Wal-Mart will not offer Sunday delivery like Amazon does or any of the streaming features right away, but could in the future.

Wal-Mart customers will be able to buy a large variety of items from toys and clothing to electronics and home goods.

Will you sign up for Wal-Mart's unlimited free shipping service in the future? Let us know with a comment below.