To participate on 99dresses, users upload a dress that they may be tired of, but that somebody else might appreciate. Unlike other clothing swap services Poshmark and Threadflip, 99dresses is aiming for the Forever 21 and Zara set, not necessarily the well-heeled worshippers of Lanvin, Balenciaga and Prada.

Also unlike its competitors, 99dresses doesn’t use any actual currency, so women who upload dresses must sell them for “buttons.” In turn they can use these buttons to buy other dresses (sortable by size), and can also buy extra buttons for a dollar each if they’re short a needed amount. The company currently monetizes by selling these buttons.

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