ysoisochrone handles the isochrones for young stellar objects (YSOs) and uses isochrones to derive the stellar mass and ages. The method uses a Bayesian inference approach. The code estimates the stellar masses, ages, and associated uncertainties by comparing their stellar effective temperature, bolometric luminosity, and their uncertainties with different stellar evolutionary models, including those specifically developed for YSOs. ysoisochrone also enables user-developed evolutionary tracks.