Online child safety campaigners including Jonathan Haidt, the bestselling writer on the mental health impacts of social media, have called on the Trump administration to investigate Roblox, the booming gaming and chat platform used by 150 million people daily, including a large number of under-13s.

Haidt’s Anxious Generation Movement, Fairplay and the rightwing anti-pornography National Center on Sexual Exploitation are among groups claiming Roblox’s design and business model conflict with children’s developmental needs.

They have filed a dossier to the Federal Trade Commission (FTC) that criticises the platform’s “engagement-maximising design features”, alleges its voice and text chat features “repeatedly expose children to sexual content and harmful adults, resulting in sexual exploitation and abuse” and says its in-game purchasing currency, Robux, monetises children’s “lack of impulse control”.

Roblox’s users include millions of young children from the age of five upward who, adopting the guise of block-like avatars, play a choice of 7 million games created by other users. They can also chat with other users depending on their age brackets. Nine-year-olds can chat with 16-year-olds and 13-year-olds can chat with 17-year-olds. The most popular game is Brookhaven, where players can “own and live in amazing houses, drive cool vehicles and explore the city”, but the site has also hosted controversial games allowing sexually explicit content, violence and horror.

The request for an investigation accuses Roblox of “committing unfair trade practices and acts at the expense of children’s safety and wellbeing”. Andrew Ferguson, the chair of the FTC, a consumer watchdog, has been outspoken about child safety online. Last year the FTC ran a seminar titled: “The attention economy: how big tech firms exploit children and hurt families.”

Roblox, based in San Mateo, California, has been growing rapidly with revenue jumping 36% to $4.9bn last year – driven by sales of the virtual currency Robux which can be used to buy virtual items on the platform. Game creators earned $1.5bn.

Haidt is the author of The Anxious Generation, which argued smartphones contributed to an international epidemic of mental illness among adolescents. Last year Haidt highlighted Roblox when he warned about “how the monetisation strategies of multiplayer games have changed, incentivising companies to put kids into harmful situations”.

Casey Mock, senior policy director of Haidt’s Anxious Generation Movement, said with previous estimates that 40% of Roblox’s daily users are under 13, “it has obligations to families that go well beyond what its terms of service may say – an obligation, at a minimum, to design a safe product. The evidence is clearly presented in this complaint that Roblox has consistently chosen profit over that obligation.”

The dossier alleges recent changes to Roblox’s text and voice-chat capabilities have not eliminated possibilities for adult-child contact and these capabilities are a source of harm to children. Roblox has recently introduced facial age estimation and other age checks, and a system called Sentinel for “real-time child endangerment detection”.

The campaigners’ intervention is the latest sign of a consumer and political backlash against online platforms that have surged in popularity, making billions for the tech companies that own them. Last month a jury in California ruled Meta and YouTube designed addictive products that harmed young people, while, in Washington, Republican legislators have been pushing forward tougher legislation to protect children online.

“Roblox claims it is safe and developmentally appropriate for children,” said Fairplay’s policy counsel, Haley Hinkle. “Our filing shows that that is simply not true. And given that over 30 million kids under age 13 are reportedly daily users of the platform, our request for an investigation is urgent. The FTC has the authority to stop Roblox from raking in billions of dollars in profit every year at the expense of our children’s safety and healthy development. We call on the commission to investigate Roblox’s unfair trade practices and acts, and to scrutinise the platform’s compliance with children’s online privacy law.”

A spokesperson for Roblox said it strongly disputes the campaigners’ claims and said its platform is “designed to provide a positive, healthy and enjoyable experience – we build for fun and connection, not short-term engagement.”

They said: “While no system can be perfect, we have a set of safeguards designed to support a safe and civil environment, and clear policies for game creators that require fair treatment of players.”

They said no one is required to buy Robux, and in the first quarter of 2026, only 1.4% of its users were payers. The company added that direct chat is off by default for players under the age of nine, and voice-chat features are restricted to age-checked players aged 13 or older.