Abstract OptQuest is a black-box optimization engine from OptTek Systems, Inc., which has developed it since 1998. You declare the decision variables, the constraints and one or more objectives. The engine proposes values for the variables, your code evaluates them and returns the results, and the engine uses those results to propose the next values. The engine does not need gradients or a formula for the objective, and it does not assume that the objective is convex or smooth.