Coherent beam combining of multiple laser beams is an attractive approach for scaling up the output power from fiber laser sources while maintaining their beam quality. A key challenge in such a beam combining approach is the need for active phase synchronization between the different amplifier arms. Stochastic parallel gradient descent (SPGD) algorithm is a popular method for synchronizing the phase across a large number of sources as it has a relatively simple hardware requirement and is scalable. In this work, we demonstrate a fiber-optic Mach-Zehnder Interferometer (MZI) with stabilized output using the SPGD algorithm implemented in a commercial controller board. We investigate the implementation of the SPGD algorithm and study key performance factors such as convergence time and output signal noise. © 2018 SPIE.