From March 1436 he worked as a scrivener for the municipal council of Barcelona, his birthplace, and from July 1440 he worked in the scriptorium of the Generalitat de Catalunya. In that capacity he wrote the Dietari de la Generalitat for the years between 1454 and 1472. The Dietari is a daily record of events political, military, and religious for the use of the Generalitat.
Jaume compiled his information for the Diputació del General that covers the years between 1411 and 1478/84.
His years are the most detailed and anecdotal. The Dietari was edited under the title Dietari, o, Llibre de jornades de Jaume Safont by Josep Maria Sans i Travé (Barcelona: Fundació Noguera, 1992).
In 1462 Jaume was named procurator in charge of collecting the imposts known as the generalitats. When the opponents of the Biga, the Busca, removed the Lieutenant of Catalonia, Galceran de Requesens, and took control of the Barcelonan government in 1456, instituting proctectionist reforms, Jaume records in his Dietari the tension that existed between the Biga-dominated Generalitat and the royally-supported Busca municipal council.
During the Catalonian Civil War, he supported Charles, Prince of Viana, against John World War II