Mobile wallets replicate physical wallets on a mobile device, in which users can store different payment instruments to make mobile payments. As the mobile wallet is adopted, a mobile payment system emerges. I study the mobile payment system of Movii—the first fintech firm in Colombia operating under a financial non-banking license for electronic deposits and payments. Based on a unique dataset of daily bilateral transfers between Movii's mobile wallet users, I build, visualize, and analyze Movii's network. Besides the anticipated increase in the number of users and the value of transfers, the visual and quantitative complexity of the network of transfers increases over time. This increase in complexity is likely to be linked to the adoption of Movii's mobile wallet. The behavior of users in the network of transfers shows that they find new ways to use mobile payments beyond person-to-person transfers, including person-to-business and business-to-business.