Portuguese hacker Rui Pinto told a Lisbon court on Friday at the opening of his trial that his "Football Leaks" are "a reason for pride and not shame".
"I was outraged by what I discovered and I decided to make it public," the 31-year-old said in a brief initial statement at the start of a trial expected to last several months.
"My job as a whistleblower is over," he added, his face covered by a mask. "I never did anything for money."
The documents Rui Pinto hacked and released to news organisations as the "Football Leaks", brought to light tax evasion and possible fraud and corruption involving star players and club officials.
Pinto faces 90 charges, including a series of computer offences and more seriously attempted blackmail against Doyen Sports, an investment fund, which triggered the investigation by filing a complaint in October 2015.
In Portugal, attempted extortion is punishable by up to 10 years in prison.
His lawyers insist he is "a very important European whistleblower" and plan to call 45 witnesses, including Edward Snowden, a former employee of the American intelligence charged with espionage, and the former French financial judge Eva Joly.
After leaking the hacked documents in 2016, Pinto fled Portugal and took refuge in Hungary where he spent four years there before being tracked down and extradited by Portugal in March 2019. On his return he was put in pre-trial detention for a year. He was released to house arrest after cooperating with Portuguese prosecutors by giving them access to a mass of encrypted unpublished documents.