The death of prominent Internet freedom fighter Aaron Swartz, who took his own life at the age of 26, weeks before he faced trial, sparked grief and anger Sunday from online rights advocates.

"Aaron did more than almost anyone to make the Internet a thriving ecosystem for open knowledge, and to keep it that way," wrote Peter Eckersley from California-based activist group Electronic Frontier Foundation.

"He refined advocacy for the progressive and open-information movement," said David Moon, program director for Demand Progress, a grassroots organization that Swartz co-founded to combat Internet censorship.

Swartz, who was just 14 when he co-developed the RSS feeds that are now the norm for publishing frequent updates online and went on to help launch social news website Reddit, hanged himself in his New York apartment on Friday.

He had been due to stand trial in April for allegedly breaking into a closet at the Massachusetts Institute of Technology to plug into the computer network and download millions of academic journal articles from the subscription-only JSTOR service.

Swartz had written openly about suffering periodically from depression, but friends and family suggested the looming trial contributed to his suicide and accused prosecutors of being over-zealous in pursuing their case.

"Aaron's death is not simply a personal tragedy. It is the product of a criminal justice system rife with intimidation and prosecutorial overreach. Decisions made by officials in the Massachusetts US Attorney's office and at MIT contributed to his death," a family statement said.

Swartz had pleaded not guilty to charges of computer fraud, wire fraud and other crimes carrying a maximum sentence of 35 years in prison and a $1 million fine.

US Attorney Carmen Ortiz, who filed the indictment against Swartz, said at the time: "Stealing is stealing whether you use a computer command or a crowbar, and whether you take documents, data or dollars."

Contacted by AFP, the attorney's office refused immediate comment on his death.

Meanwhile, tributes poured in from friends, former colleagues and Internet luminaries alike.

"Aaron dead. World wanderers, we have lost a wise elder. Hackers for right, we are one down. Parents all, we have lost a child. Let us weep," Tim Berners-Lee, inventor of the World Wide Web, wrote in one tweet.

"Aaron had an unbeatable combination of political insight, technical skill, and intelligence about people and issues," wrote prominent blogger and friend Cory Doctorow.

"I think he could have revolutionized American (and worldwide) politics. His legacy may still yet do so."

Contributors to a memorial page set up online in Swartz's honor included many strangers who simply believed in his cause and wanted to share their sense of loss.

"Though I never met Aaron, I believe all of us who value freedom of expression and the ability to share information around the world instantly via the Internet, owe him a huge debt of gratitude," wrote Fiona Bateson.

"A hacker with a conscience extraordinaire, a brilliant, compassionate young man who fought for the rights of all those who believe in information freedom and network neutrality: We love you Aaron, and you will be sorely missed."

Several reactions to Swartz's suicide were tinged with bitterness and some directly attacked prosecutors for relentlessly pursuing serious criminal charges that they argued were trumped up.

"We need a better sense of justice," wrote Harvard law professor Lawrence Lessig, faculty director for the Edmond J. Safra Center for Ethics, where Swartz was once a fellow.

"The question this government needs to answer is why it was so necessary that Aaron Swartz be labeled a 'felon,'" Lessig blasted.

Two years before the MIT incident, the FBI launched an investigation after Swartz released a trove of US federal court documents online that are usually only accessible at a fee through the government's Public Access to Court Electronic Records, or PACER.

In 2008, that fee was eight cents per page.

According to the FBI's profile of Swartz, which he obtained and posted online, the activist had inundated the PACER system with requests in September 2008 at the rate of one prompt every three seconds.

In less than three weeks, he managed to download more than 18 million pages with an estimated value of $1.5 million to his home in the Chicago suburb of Highland Park.

A post on Swartz's memorial site, rememberaaronsw.tumblr.com, said his funeral would be held on Tuesday in Chicago: "Friends, family and admirers all welcome."