In this paper we analyze a new model of crowdfunding recently introduced by Bolstr and Localstake. In this model, a platform acts as a matchmaker between a firm needing funds and a crowd of investors willing to provide capital. Once the firm is funded, it pays back the investors using revenue sharing contracts, with a pre-specified investment multiple (investors will receive M ≥ 1 dollars for every dollar invested) and a revenue-sharing proportion, over an investment horizon of uncertain duration. The firm determines its optimal contract parameters to maximize its expected net present value, subject to investor participation constraints and platform fees. A natural multi-period formulation results in a non-convex stochastic optimization problem, which we solve numerically using Monte Carlo simulation and a grid-based optimization framework, for normally distributed cash flows that are parameterized using real data from Bolstr.