The International Consortium of Investigative Journalists (ICIJ) is a collective of 190 journalists spanning more than 65 countries seeking to root out cross-border crime, corruption and abuse of power.
This week it distributed 11.5 million documents compiled by more than 100 newspapers that expose secret offshore financial dealings of 140 political figures, including 12 current or former heads of state along with celebrities in sports and show business.
They go from a close confidant of Russian President Vladimir Putin to relatives of Chinese President Xi Jinping, and from Ukrainian President Petro Poroshenko to Icelandic Prime Minister Sigmundur David Gunnlaugsson.
In terms of size, "the 'Panama Papers' is likely the biggest leak of inside information in history," according to ICIJ.
The documents, from around 214,000 offshore entities, came from Mossack Fonseca, a Panama-based law firm with offices in more than 35 countries.
Founded in 1997 by US journalist Chuck Lewis and based in Washington, the ICIJ is a non-profit organization that has a small staff and a low-key profile.
It is funded by charities and private donations, according to its website.
The ICIJ is now run by Australian journalist Gerard Ryle, who emigrated to the United States in 2011 with details of 2.5 million digital files, a treasure trove that would ultimately yield information on 120,000 offshore companies and nearly 130,000 individuals.
Modeled on the WikiLeaks whistleblowing site which gained global notoriety by publishing millions of leaked diplomatic cables, ICIJ relies on respected global press organizations such as Le Monde, the South China Morning Post, the BBC, the Washington Post, Folha de Sao Paulo and the Sueddeutsche Zeitung to help it gather information.
"Globalization and development have placed extraordinary pressures on human societies, posing unprecedented threats from polluting industries, transnational crime networks, rogue states and the actions of powerful figures in business and government," the ICIJ website says.
Its teams have "exposed smuggling by multinational tobacco companies and by organized crime syndicates, investigated private military cartels, asbestos companies and climate change lobbyists and broke new ground by publicizing details of Iraq and Afghanistan war contracts," it adds.
In April 2013, the ICIJ posted online a "who's who" of people and entities hiding assets offshore, describing the scoop as "probably the biggest international journalistic collaboration in history" until then.
"Offshore leaks" exposed the identities of thousands of holders of foreign accounts, including the wife of Igor Shuvalov, who is currently Russia's first deputy prime minister.
In January 2014, ICIJ scored a new coup with revelations that China's elite was also parking money in offshore tax havens.
In November 2014, the consortium revealed "LuxLeaks," a trove of leaked documents showing that hundreds of the world's biggest companies, including AIG, Amazon, Apple, IKEA, Pepsi and Verizon had brokered secret deals with Luxembourg to avoid paying billions of dollars in taxes.
Finally, in February 2015, the ICIJ uncovered "SwissLeaks," a scheme that allegedly helped clients of banking giant HSBC's Swiss division evade taxes on accounts worth $119 billion.
The ICIJ benefitted from files stolen by a former employee in 2007 that contained information on more than 100,000 people.