SAN FRANCISCO — Emmett Shear, the chief executive of the livestreaming site Twitch, said on Thursday that he was resigning, ending a 16-year tenure for the co-founder of the platform favored by video game enthusiasts.
Mr. Shear said in a blog post that he was stepping down because he had just had a child. He said that Dan Clancy, Twitch’s president, would take over as chief executive, and that Mr. Shear would remain at Twitch in an advisory role.
“Twitch often feels to me like a child I’ve been raising as well,” he wrote. “And while I will always want to be there if Twitch needs me, at 16 years old it feels to me Twitch is ready to move out of the house and venture alone.”
Mr. Shear leaves a platform with big challenges, but also one that has grown drastically in recent years and become the cultural center of the video game world. Now, livestreamers who broadcast themselves gaming, cooking or chatting with fans can attract audiences of thousands and earn millions of dollars on the site, which is owned by Amazon.
The platform started in 2007 as Justin.tv, a livestreaming project following the life of Justin Kan, who started the site with Mr. Shear and two others. Mr. Shear wrote that he “thought at the time that we would most likely fail and give up in less than a year.”
Instead, the site became a hub for live video and transitioned into Twitch in 2011, a place where video game players streamed their play. In 2014, Amazon bought the site for $1 billion.
As Twitch has grown, it has faced the same questions as other social platforms, such as how it should regulate harmful content and keep its users happy. It also faces the question of how best to cater to its star content creators, many of whom have been lured away to rival platforms like YouTube. In the past several years, Twitch creators have called out the platform for not doing enough to protect them from stalkers and online harassment, and complained that the site took too high a cut of their earnings.
Despite the controversy, Twitch has continued to thrive. The site now attracts seven million streamers each month and 31 million viewers daily.
Now, Mr. Clancy, who was already running the site’s day-to-day operations, will take over. A longtime Google employee and Nextdoor executive, he lacks the video game background of Mr. Shear, a fervent player of the game StarCraft.
“It’s a strength and a weakness,” Mr. Clancy said of his lack of a gaming background in an interview last year. “It’s a strength because I don’t come to Twitch with these preconceived ideas of Twitch.”