A zealous advocate of public online access, Swartz was extolled Saturday by those who believed as he did. He was "an extraordinary hacker and activist," the Electronic Frontier Foundation, an international nonprofit digital rights group based in California wrote in a tribute on its home page.
"Playing Mozart's Requiem in honor of a brave and brilliant man," tweeted Carl Malamud, an Internet public domain advocate who believes in free access to legally obtained files.
Swartz co-founded the social news website Reddit, which was later sold to Conde Nast, as well as the political action group Demand Progress, which campaigns against Internet censorship.
He also apparently struggled at times with depression, writing in a 2007 blog post: "Surely there have been times when you've been sad. Perhaps a loved one has abandoned you or a plan has gone horribly awry. ... You feel worthless. ... depressed mood is like that, only it doesn't come for any reason and it doesn't go for any either."
Harvard law professor Lawrence Lessig, faculty director for Safra Center for Ethics where Swartz was once a fellow, wrote: "We need a better sense of justice. ... The question this government needs to answer is why it was so necessary that Aaron Swartz be labeled a 'felon.'"
Before the Massachusetts' case, Swartz aided Malamud in his effort to post federal court documents for free online, rather than the few cents per page that the government charges through its electronic archive, PACER. Swartz wrote a program in 2008 to legally download the files using free access via public libraries, according to The New York Times. About 20 percent of all the court papers were made available until the government shut down the library access.