Poor diet is a leading cause of death and disease globally. This epidemic requires effective and accessible interventions to stop the increasing number of diet-related deaths and the health and economic impacts of diet-related disease. Online interventions provide flexibility and accessibility. With the ubiquitous use of smartphones, they can be intertwined with daily activities such as shopping and eating. The aim of this review is to determine what features and behavior change techniques employed in online dietary interventions for adult populations promoting dietary behavior change.