This study explores the potential of chatbots in promoting sustainable travel practices among domestic tourists in the Gili Islands, Indonesia. The research aims to conceptualize a chatbot that can facilitate pro-environmental behavior (PEB) spillover, where tourists continue to act sustainably after their trip. The study uses an exploratory qualitative approach, including semi-structured interviews, focus group discussions, and field observations, guided by Service Design and Grounded Theory. The findings suggest that chatbots can be effective tools for nudging tourists to maintain sustainable behaviors post-travel by providing reminders of their past PEBs and educating them on the positive impacts of their actions. The study also develops a theoretical model linking chatbot adoption and PEB spillover, highlighting the importance of factors such as perceived usefulness, personalization, and environmental awareness. The chatbot is designed to be accessible via WhatsApp, leveraging its popularity in Indonesia. The study concludes that chatbots can play a significant role in promoting sustainable tourism by influencing tourists' behavior and encouraging long-term responsible actions. The findings have implications for policymakers and tourism providers, suggesting that chatbots can be a valuable tool in advancing sustainable tourism practices. The study also highlights the need for further research into the effectiveness of chatbots in promoting PEB spillover and the importance of aligning technological innovations with government agendas to ensure their success.This study explores the potential of chatbots in promoting sustainable travel practices among domestic tourists in the Gili Islands, Indonesia. The research aims to conceptualize a chatbot that can facilitate pro-environmental behavior (PEB) spillover, where tourists continue to act sustainably after their trip. The study uses an exploratory qualitative approach, including semi-structured interviews, focus group discussions, and field observations, guided by Service Design and Grounded Theory. The findings suggest that chatbots can be effective tools for nudging tourists to maintain sustainable behaviors post-travel by providing reminders of their past PEBs and educating them on the positive impacts of their actions. The study also develops a theoretical model linking chatbot adoption and PEB spillover, highlighting the importance of factors such as perceived usefulness, personalization, and environmental awareness. The chatbot is designed to be accessible via WhatsApp, leveraging its popularity in Indonesia. The study concludes that chatbots can play a significant role in promoting sustainable tourism by influencing tourists' behavior and encouraging long-term responsible actions. The findings have implications for policymakers and tourism providers, suggesting that chatbots can be a valuable tool in advancing sustainable tourism practices. The study also highlights the need for further research into the effectiveness of chatbots in promoting PEB spillover and the importance of aligning technological innovations with government agendas to ensure their success.