Dataset for The use of food swaps to encourage healthier online food choices. Online grocery stores offer opportunities to encourage healthier food choices at the moment that consumers put a product of their choice in their basket. This study aims to examine the effect of a swap offer, Nutri-Score labelling and a descriptive norm message on the healthiness of food choices in such an online food basket. Additionally, it is examined whether these interventions make it more motivating and easier for consumers to select healthier food choices and whether potential effects are moderated by consumers’ health interest. Hypotheses were tested in a simulated online supermarket. Dutch participants (n=550) chose their preferred product out of six product options for four different categories (breakfast cereals, crackers, pizza and muesli bars). Participants were randomly allocated to one of eight groups based on the interventions (Nutri-Score, swap offer, norm message and the five different combinations). Primary outcome was the difference in nutrient profiling (NP) healthiness score of product choices, for which a lower score represents a healthier product. Results show that a swap offer (NP score M=10.52, SD =16.15) and Nutri-Score labelling (NP score M=15.38, SD=15.24) significantly improved NP healthiness scores compared to the control condition (NP score M=18.03, SD=14.02), whereas a norm message did not (NP score M=17.96, SD=15.15). These findings provide valuable insights for policy makers and practitioners on the implementation of swap offers and Nutri-Score labelling in the online store environment.