Giovanni of Ser Giovanni from Mone Cassai was Masaccio’s younger brother. He was born from Giovanni and Jacopa; surely influenced in the choice of his profession by his grandfather Mone Cassaio, specializing in the construction of Cassoni, he subscribed himself at the Art of Doctors and Apothecaries in 1430. He came in Florence in 1417 probably with his brother and he was apprentice at the shop of Bicci di Lorenzo with Andrea di Giusto and Stefano d’Antonio Vanni.
In 1426 he helps his brother in the execution of the Polypthych of the Carmine in Pisa. Between 1436 and 1440 he cooperates at the execution of inlays in the Sacristy of the Florentine Dome. He frescoes the Church of S.Lorenzo in San Giovanni, in cooperation with the florentine Paolo Schiavo. His wide artistic activity includes also particular objects such as chests fronts, headboards or deschi da parto, related to the decoration and furnishing of florentine houses.