Customer interactivity is crucial for the performance of new product development within firms, which essentially involves an information processing process. With the rise of cross-border e-commerce, the interaction with multinational customers faces a new challenge of language friction, which intensifies the complexity of information processing. However, existing research does not clarify the role of language friction in the relationship between customer interactivity and new product development performance. Drawing on the information processing theory, this article aims to explore the impact of customer interactivity on new product development performance and the moderating effect of language friction for cross-border e-commerce firms. By collecting questionnaire data from 275 cross-border e-commerce firms, this study measures the key concepts of customer interactivity and new product development performance using scales. Subsequently, we match the questionnaire data with secondary databases such as national statistical bureaus, Ethnologue, and WALS, to calculate the value of language friction.Reliability and validity analyses of the scale data underscore the high quality and adherence to predefined criteria. The covariance tests reveal that common method bias exerts no discernible impact on the results of the study. Regression analyses ascertain that customer interactivity in cross-border e-commerce firms augments new product development performance. This is because customer interactivity can provide cross-border e-commerce firms with more valuable information related to new product development and enhance the efficiency and ability of firms to process information. In addition, language friction manifests an inverted U-shaped moderating effect in the relationship between customer interactivity and new product development performance. In other words, the positive impact of customer interaction in cross-border e-commerce firms on new product development is most pronounced at a moderate level of language friction.This study has several theoretical contributions. First, it contributes to the literature on customer interactivity and new product development by introducing a cross-border context, underscoring the pivotal role of language friction as a moderator in this relationship. Additionally, this study enriches the research related to information processing theory on customer interactivity and new product development in cross-border scenarios.Moreover, this study imparts managerial insights for enhancing the new product development performance of cross-border e-commerce firms. Since customer interactivity is conducive to enhancing the new product development performance of cross-border e-commerce firms, leveraging customer interactivity through diverse social media and online platforms is advocated, with an emphasis on tailoring strategies based on the level of language friction. When firms are operating under a moderate level of language friction, such as in the United States, the United Kingdom, Mauritius, Zambia, and Australia, customer interactivity contributes most to new product development and can be an important source of innovation. Conversely, when firms are operating in a low or high level of language friction, such as Singapore, Thailand, Vietnam, France, and Ethiopia, the positive impact of customer interactivity for new product development is less pronounced. Consequently, innovation-centric firms are encouraged to channel more inputs towards countries with moderate language friction, positioning them as primary sources of innovation.