Study Design and Participants
This study was a 2-arm double-blind RCT conducted in 5 cities in China (Baotou, Beijing, Dezhou, Linzi, and Yakeshi). Participants were randomized to the intervention or control group between April 1 and July 27, 2021. Daily or weekly smokers 18 years or older were eligible for inclusion if they owned a mobile phone and used the app. Exclusion criteria included receipt of any smoking cessation treatment within 30 days and a diagnosis of any mental illness (current or past). This trial was reviewed and approved by the ethics committee of the Peking University Health Science Center. The trial protocol is provided in 