Mr Barlow, a co-founder of the Electronic Frontier Foundation (EFF) that campaigns on digital rights issues was a director of the organization for many years.
He was an advocate of freedom of speech and wrote about the net’s potential for making society more representative.
Mr Barlow alsoran a cattle ranch and spent years writing lyrics for the Grateful Dead rock group
Bob Weir, one of the band’s founding members, tweeted that Mr Barlow would “live on in the songs we wrote”.
This life is fleeting, as we all know – the Muse we serve is not. John had a way of taking life’s most difficult things and framing them as challenges, therefore adventures. He was to be admired for that, even emulated. He’ll live on in the songs we wrote…
Cindy Cohn, director of the EFF, announced Mr Barlow’s death saying that he died quietly in his sleep on 7 February. Mr Barlow had been ill for several years but few details were given about his medical problems.
“It is no exaggeration to say that major parts of the internet we all know and love today exist and thrive because of Barlow’s vision and leadership,” said Ms Cohn.
Mr Barlow’s interest in digital rights grew out of his involvement with the Well – one of the earliest electronic chat forums. He was among the first to describe such virtual forums as “cyber-space” and to argue that the novel territory demanded new rules, behaviours and laws.
The EFF grew out of the work he did with some of the Well’s high-profile members who got into trouble with the police and FBI for a variety of alleged computer crimes.
In 1996, he wrote the widely quoted Declaration of the Independence of Cyberspace, which asked governments of the world to stop meddling in the affairs of net-centred communities.
“You are not welcome among us. You have no sovereignty where we gather,” he wrote.
In her eulogy, Ms Cohn of the EFF defended Mr Barlow against charges that he promoted a view of the net as a force that would bring about positive social change with few consequences.
“Barlow knew that new technology could create and empower evil as much as it could create and empower good. He made a conscious decision to focus on the latter,” she said.