Swartz is believed to have comitted suicide in New York City on Friday (January 11).
The Guardian reports that Swartz's lawyer Ellito R Peters emailed MIT university newspaper The Tech to confirm the news, saying: "The tragic and heartbreaking information you received is, regrettably, true."
The freedom of information activist had been facing a trial over allegations that he had hacked JSTOR, a digital library of academic journals, with the intention of making their contents available on peer-to-peer sharing sites.
Swartz surrendered to the authorities immediately in relation to the charge but pleaded not guilty - if convicted, he would have faced a lengthy prison term.
The 26-year-old was a prodigious talent in the field of programming, being part of the group that wrote the RSS 1.0 script, a code that remains in use today, aged just 14.
Swartz also co-founded Reddit before leaving his position there in 2007, as well as creating the web.py web application framework and co-founding Demand Progress, a progressive advocacy group.
Blog posts from 2007 suggest that Swartz had suffered from chronic depression. Cory Doctorow, founder of influential geek and technology blog Boing Boing, wrote in an eulogy today (January 12): "We have all lost someone today who had more work to do, and who made the world a better place when he did it."