Systems and methods for sharing personalizable cards via a computerized card service are provided. One disclosed method includes, at a card client program executable on a computing device, creating a personalizable card having extensible data, and sending a first instance of the personalizable card to a card service program. The method may further include, at the card service program, propagating the first instance of the personalizable card to a peer of the user, and at the card client program, updating the extensible data of the personalizable card. Upon updating the extensible data, the method may further include sending a second instance of the personalizable card to the card service program, and propagating the second instance of the personalizable card to the peer of the user. The personalizable card may be propagated according to propagation permissions set by the user.