New digital banks and lenders are proliferating, with incumbents joining the ranks of fintech startups to capitalize on new digital business models. As the heads of these new ventures plot their vision and revenue streams, they risk neglecting one key decision: the banking technology of the new business. Tech leaders must guide their colleagues through the available technology options, as the "tech" of the fintech will affect not only the venture's innovation, budget, and timescale but also the parent's bank transformation and resources.