The Grooveshark co-founder Josh Greenberg was found dead in his bed on Sunday 19 July by his girlfriend.
Josh Greenberg's mother Lori told the Gainesville Sun newspaper that her son was in good spirits. "He was excited about potential new things that he was going to start," Mrs Greenberg said, adding that she did not believe he had any health concerns.
There was no evidence of foul play or suicide say Florida police. The medical examiner's autopsy found no explanation for a cause of death, but toxicology results would be done in two or three months.
Grooveshark closed in April following many years of legal action from record labels.
A US court stated that the website could be liable for $736m (£472m) in damages after it was judged to have wilfully breached copyright when building the service's music library, according to BBC News.
When the owners closed Grooveshark, they issued a statement which read: "Despite [the] best of intentions, we made very serious mistakes. We failed to secure licenses from rights holders for the vast amount of music on the service.
"That was wrong. We apologise. Without reservation."
At its peak, Grooveshark had up to 40 million users a month and 145 employees.
Colleagues posted their tributes to Greenberg on Twitter. "The world lost a great entrepreneur," wrote engineer Tyler Nettleton.
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