China’s top internet watchdog said on Friday tech giants such as Tencent Holdings and Alibaba Group have submitted details of algorithms used in some of their products, complying with a drive by authorities to tighten oversight of platform algorithms.

The rules are part of a broad regulatory crackdown by Beijing against its once free-wheeling technology sector. State media had accused internet platforms of using algorithms to invade user privacy and influencing their choices.

The Cyberspace Administration of China (CAC) published a list of 30 algorithms used in some of the country’s most popular apps, including Alibaba’s Taobao，Tencent’s Wechat，Meituan and ByteDance’s Douyin, with brief descriptions of their use and gave them classification numbers.

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It was the first list it published since China in March passed new regulations for algorithm recommendation services and launched a filing system requiring firms to companies to disclose they used in their apps.

The CAC’s list, for instance, said the Taobao app had logged with it a recommendation algorithm that crunched each user’s visit and search history to recommend them products and services, while Meituan had provided details of the algorithm it used to estimate delivery times and match riders.

Other companies on the list included Chinese online search giant Baidu, short video platform Kuaishou and microblogging site Sina’s Weibo.

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