Amazon Go is headed for Chicago and San Francisco.

The retailer, which opened its first cashierless concept to the public in Seattle in January, is seeking store managers in both cities, according to recent job postings on Amazon's website. In response to an inquiry, a spokesperson confirmed that the company was planning to open stores in each city, but didn't specify when.

Amazon executives had hinted during the January opening of the pilot store on the company's Seattle headquarters campus that they planned to expand, but the company had been silent on its .

There were earlier signs that Amazon had its eye on Chicago and San Francisco.

Real-estate tracker Curbed in February spotted a building permit for construction of a 625-square-foot "Amazon store" in Chicago's Loop district. And on Sunday, the San Francisco Chronicle reported that Amazon planned to open a store near the city's Union Square, with a formal announcement expected within weeks.

Reports hint at other location possibilities.

In February, Recode reported that Amazon was in talks with a Los Angeles developer about placing a store there, and that it might also open new locations in Seattle. The story said the company could open as many as six storefronts in 2018, citing people familiar with the plans.

Customers, who need to have Amazon's Go , swipe their phone on the way into the store. After that, Amazon's system uses cameras and other sensors to track shoppers and identify what they take off shelves. No checkout is required; people are charged for the items they take shortly after leaving the store.

The system, which Amazon calls "just walk out shopping," ran into some technical difficulties during nearly 14 months of employee-only trials, people familiar with the matter said.