Audio-only social network iPhone app Clubhouse has seen an explosion of new users in the last week, including Chinese people discussing politics.
According to mobile analytics firm Sensor Tower, the app was downloaded 2.3 million times by 31 January.
The chat app is free, but currently invite-only.
However, Chinese users are paying up to $77 (£56) for invitations from e-commerce sites, according to the FT.
Clubhouse was launched in May and valued at almost $100m. The app allows users to join and participate in pop-up public or private audio chatrooms.
Conversations are not recorded, which theoretically ensures privacy, although some interviews of celebrities and influencers have been secretly recorded and uploaded to YouTube.
Early adopters were mostly Silicon Valley technophiles and investors, but the app’s invite-only nature has created an exclusivity appeal that has seen a raft of US celebrities join, including Oprah Winfrey, Ashton Kutcher, Drake, Azealia Banks, Jared Leto and Tiffany Haddish.
But the app’s downloads more than doubled in the last two weeks due to popular tech moguls like Elon Musk and Mark Zuckerberg joining Clubhouse to participate in interviews and talk shows.
After Mr Musk tweeted that he would be speaking live on the app, Clubhouse’s shares soared 117% on 1 February.
Freedom to discuss controversial topics
At the moment, Clubhouse is only available on the iPhone and can be accessed in mainland China without the use of a virtual private network (VPN) to bypass China’s Great Firewall.
While many of the chatrooms are either private or have been deleted, over the weekend thousands of Chinese users joined chatrooms on Clubhouse in order to freely discuss topics that are considered to be taboo in China, from the Hong Kong protests and the treatment of Uighurs in Xinjiang, to heightening tensions between China and Taiwan.
Multiple Chinese users who witnessed the audio conversations in the app’s chatrooms took to Twitter to discuss what they were seeing.
User Arendt HuTong said on Twitter that he listened to a conversation between Uighurs, journalists and Chinese “that were so sincere and peaceful that it made me want to cry”, while in another conversation, young people in mainland China listened to the latest updates from people in Hong Kong and expressed their sympathies.
“For Chinese users, the biggest significance of clubhouse is probably the uncensored communication between ordinary people,” he wrote on Twitter (translated from Mandarin).
US-based podcaster Kaiser Kuo said that the chatrooms contained “fantastically candid” comments.