1. A computer implemented method comprising: in an electronic, network commerce system, causing one or more hardware-implemented processors to execute instructions, the instructions causing the one or more processors to perform operations comprising: receiving a listing submitted by a seller, the listing describing an attribute of an item for sale by the seller; selecting a profile for a user from a plurality of profiles using at least one characteristic of the user determined from data collected about the user's navigational activities on the network commerce system, each respective profile of the plurality of profiles associated with users that have a common characteristic that is different from the other users associated with the plurality of other profiles; receiving a seller-specified rule, the rule specifying a modification of the attribute in the listing for a given profile in the plurality of profiles; and creating a modified listing by applying a rule from the plurality of rules corresponding to the particular profile associated with the user to modify the attribute; causing a display of the modified listing on a user interface, in response to receiving a browsing activity via the user interface.