We have described the development of a new micro-payment system, NetPay, f- turing different ways of managing electronic money, or e-coins. NetPay provides an off-line, anonymous protocol that supports high-volume, low-cost electronic trans- tions over the Internet. We developed three kinds of e-wallets to manage coins in a NetPay-based system: a sever-side e-wallet allowing multiple computer access to- coins; a client-side e-wallet allowing customer PC management of the e-coins, and a cookie-based e-wallet cache to improve performance of the client-side e-wallet c- munication overhead....