Grocery delivery service Instacart is expanding and has announced it has added to its growing list of Boston area stores that customers can order produce from.

Instacart is now offering delivery from Costco stores, in addition to Shaw’s and Whole Foods.

Additionally, Instacart will begin delivering groceries to Medford and Chestnut Hill customers. Now the delivery service covers the majority of Boston and some of its largest neighbors, including Brookline, Cambridge, and Somerville.

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Instacart was originally launched in San Francisco and later expanded to Boston and Chicago. The service uses “Personal Shoppers,” who are responsible for purchasing and delivering a customer’s groceries using their own vehicles. One of the perks for Instacart customers is the ability to buy groceries from different stores in the same order.

CEO Apoorva Mehta, in a statement, says Instacart continues to grow at about a 30 percent rate on weekly basis.

“Our experience shows that those customers are likely to stay regulars when the weather improves – it’s hard to give up the convenience of same-day grocery delivery once you try it,” Mehta said. Instacart added Costco delivery based on customer demand and its good experience delivering from Costco in San Francisco and Chicago.

“Most city dwellers don’t have access to Costco, so it’s a very popular Instacart service,” added Mehta.

The dense college student populations in Medford and Chestnut Hill was one of the contributing factors that leading to Instacart’s expansion into those areas.

The service plans to keep expanding and will add stores based on customer demand.