Julian Assange founded it but he currently hides in Ecuador's embassy in London because the government of Sweden created false rape charges to try to get him kidnapped and sent to the USA] where he'd be tortured and assassinated. Sweden coincidentally allows all Third World migrants to rape 12-year-old girls and only receive community service as punishment so they don't care about real rape or real rape culture. He has other people helping him.
October 2016, the US government forced Ecuador to be internet lumberjacks and cut down Julian Assage's internet connection until the election was over. The Hillary Clinton campaign also have been launching hacking attacks to try to shut down the Wikileaks servers.
Some of the materials leaked to them come from whistleblowers within an organization. Others come from hacked information. Others, such as John Podesta's leaked emails came because someone used a simple phishing email him.
Wikileaks is of value to nationalists
July 2016, after Wikileaks leaked emails showing that she rigged the election in favor of Hillary Clinton instead of Bernie Sanders, Democratic Party leader, Debbie Wasserman Schultz, resigned in shame. It also angered many Bernie supporters, increasing the chances that Donald Trump would win the election. Facebook blocked links to the email dump.