Move over, Etsy and Shopify. Popular mobile-transactions startup Square is branching out beyond processing in-person payments. Starting today, it wants to help businesses sell their wares online, too. Square has created Square Marketplace, an ecommerce service allowing businesses to sell their products and services online.

"People are already using Square on their smartphones and tablets to sell things offline," says Jack Dorsey, co-founder of Square and Twitter. "With Square Market, they have an online marketplace that enables … local businesses to go from neighborhood to national in an affordable way."

The idea is to eliminate the time and expense required for business owners to create their own dedicated ecommerce websites, says Ajit Varma, Square's director of discovery. Any business -- whether it is already using Square's mobile payments reader and app or not -- can set up a page for free. The page includes information such as the company's name, contact information, photos and items it is selling.

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On the Square Market site, customers will be able to search for individual merchants or by the items they are looking for, Varma says. Business owners will be able to promote the items and services they're selling over Twitter and other social media.

Customers can make purchases directly through the marketplace using the Square Wallet app or by entering their credit card information. When a product or service is sold, Square's fee is 2.75 percent of the sale price -- the same rate Square charges for its mobile payments service.

Already, 120 merchants have signed up to participate in the Square Market, Varma says. The service is live for all businesses starting today.

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