INTRODUCTION Chatbots emulate human-like interactions and may usefully provide on-demand access to tailored smoking cessation support. We have developed a prototype smartphone application-based smoking cessation chatbot, named Quin, grounded in real-world, evidence- and theory-based smoking cessation counselling sessions.

METHOD Conversation topics and interactions in Quitline counselling sessions (N=30; 18 hours) were characterised using thematic, content, and proponent analyses of transcripts. Quin was created by programming this content using a chatbot framework which interacts with users via speech-to-text. Reiterative changes and additions were made to the conversation structure and dialogue following regular consultation with a multidisciplinary team from relevant fields, and from evidence-based resources.

RESULTS Chatbot conversations were encoded into initial and scheduled follow-up 'appointments'. Collection of demographic information, and smoking and quit history, informed tailored discussion about pharmacotherapy preferences, behavioural strategies, and social and professional support to form a quit plan. Follow-up appointments were programmed to check in on user progress, review elements of the quit plan, answer questions and solve issues. Quin was programmed to include teachable moments and educational content to enhance health literacy and informed decision-making. Personal agency is encouraged through exploration and self-reflection of users' personal behaviours, experiences, preferences and ideas.

CONCLUSION Quin's successful development represents a movement towards improving access to personalised smoking cessation support. Qualitative foundations of Quin provide greater insight into the smoking cessation counselling relationship and enhances the conversational ability of the technology. The prototype chatbot will be refined through beta-testing with end-users and stakeholders prior to evaluation in a clinical trial.

IMPLICATIONS Our novel study provides transparent description of the translation of qualitative evidence of real-world smoking cessation counselling sessions into the design and development of a prototype smoking cessation chatbot. The successful iterative development of Quin not only embodies the science and art of health promotion, but also a step-forward in expanding the reach of tailored, evidence based, in-pocket support for people who want to quit smoking.