Abstract: A prosthetic ankle device and methods are provided herein to adjust stiffness of the prosthetic ankle. The prosthetic ankle including a base, and a vertical support having a first end pivotally coupled to the base. The prosthetic ankle may also include a first cantilever beam spring having a fixed end coupled to the base such that a length of the first cantilever beam spring in an unloaded position is substantially parallel to a longitudinal axis of the vertical support when (he vertical support is in a neutral position. The prosthetic ankle may also include a stiffness regulator movably coupled to the vertical support. The stiffness regulator may include a platform that defines a first contact surface adjacent the first cantilever beam spring. In addition, the stiffness regulator may pivot with the vertical support relative to the base.