Digital Trojan horse – urban tools in a non-urban environment. How to inform tourist travel decisions by means of a multi-service mobile app

• Three discrete Choice Experiments to study impacts of mobile app on tourist travel decisions. • App importance is low, but increases in complex and time-sensitive stages of travel. • Absolute effect on market shares is minor, but relative changes are substantial. • The app is a "digital Trojan horse" unobtrusively promoting sustainable travel. This study examines the impact of a multi-service mobile app on tourist decision-making across three key stages: destination selection, long-distance travel, and local mobility at the destination. Utilizing discrete choice experiments (DCEs) with 266 survey participants, the study evaluates the effects of an app that integrates information and booking interface for transportation, attractions, and local facilities. The results highlight that while the impact of the app is generally low, its added value becomes more substantial in complex and time-sensitive stages of travel, such as on-site mobility. The app’s availability increases the market share of destinations by up to 4.5 percentage points and increases the attractiveness of rail travel by 27 % under specific scenarios. The willingness to pay for the app is in the range of 7-12 € per night for destination choice, 10–20 € for mode choice for long-distance travel to destination, and 1-1.28 € per trip for local trips at the destination, indicating that it is commercially viable to develop and maintain. Despite these benefits, the app's effectiveness is contingent on user awareness and integration with high-quality local transport services. The study introduces the app as a "digital Trojan horse," leveraging its functionalities to unobtrusively promote sustainable travel options. This research underscores the need for collaborative app development across destinations and suggests further investigation into large-scale deployment and heterogeneity in user preferences.