The identification of Cagliostro with Giuseppe Balsamo, born in Palermo in 1743 to a modest family, is mainstream and rests substantially on the Inquisition's own biography of him, compiled from his trial. A rehabilitating tradition going back to W. R. H. Trowbridge in 1910 has argued that the Inquisition's account is prosecution material and unreliable; that argument is mostly directed at the charge of charlatanry rather than at the identification itself, and it has not displaced the consensus.
What is documented is a decade of extraordinary success. He and his wife Serafina moved through the courts and lodges of Europe, London, Courland, St Petersburg, Warsaw, Strasbourg, Paris, offering healing, an elixir, and initiation into an Egyptian Rite of Freemasonry of his own devising, which admitted women in its own lodges and claimed a descent from Egyptian antiquity that it did not have. He was received seriously by people who were not fools, and he does not appear to have charged the poor.
He was arrested in 1785 over the Affair of the Diamond Necklace, the confidence swindle in which the Cardinal de Rohan was defrauded of a fortune in the queen's name. Cagliostro was imprisoned in the Bastille, tried, and acquitted, a fact usually omitted by writers who use the affair to establish that he was a fraud. He was expelled from France regardless.
The end is not disputed. He went to Rome, was denounced to the Inquisition in 1789 for Freemasonry and heresy, was condemned to death, had the sentence commuted to life, and died in the fortress of San Leo in 1795.