California introduces age verification law for all operating systems, including Linux and SteamOS — user age verified during OS account setup

(Image credit: Valve)
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California's Digital Age Assurance Act (AB 1043) , signed by Governor Gavin Newsom in October 2025, requires every operating system provider in California to collect age information from users at account setup and transmit that data to app developers via a real-time API, with the law taking effect on January 1, 2027.

The law's broad definition of an "operating system provider" — anyone who "develops, licenses, or controls the operating system software on a computer, mobile device, or any other general purpose computing device" — pulls in not just Windows, macOS, Android, and iOS, but Linux distributions and Valve's SteamOS .

According to AB 1043, OS providers must maintain a "reasonably consistent real-time application programming interface" that categorizes users into four age brackets — under 13, 13 to under 16, 16 to under 18, and 18 or older — and hand that signal to any developer who requests it when their app is downloaded or launched.

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Contributor

Luke James is a freelance writer and journalist.  Although his background is in legal, he has a personal interest in all things tech, especially hardware and microelectronics, and anything regulatory.