Aaron Swartz, the Internet activist who co-founded Reddit and co-wrote the initial specification for RSS, has committed suicide, a relative told CNN Saturday. He was 26.

Swartz also co-founded Demand Progress, a political action group that campaigns against Internet censorship.

"Great minds carry heavy burdens," wrote one Reddit user on Saturday.

Swartz also faced legal troubles in recent years. In 2011, he was arrested in Boston for alleged computer fraud and illegally obtaining thousands of documents from protected computers. Two years earlier, the FBI investigated him after he released millions of U.S. federal court documents online. No charges were filed.