The problem of intimate partner violence (IPV) and its mental health effects on women are significant in New Zealand. Our overall goal is to develop culturally appropriate and accessible interventions for women that limit IPV and its negative consequences. One of the most widely recommended interventions is safety planning. A safety decision aid, weighing the dangers of leaving or staying in a relationship, gives women the opportunity to prioritise and plan safety for themselves and their children. Using an experimental design, we will test the effectiveness of an interactive internet-based safety decision aid. In this study, 340 abused women will be assigned by chance in equal numbers to either a safety decision aid intervention or control website. Women will be asked to self-report online their decisional conflict related to an abusive relationship, their safety-seeking behaviours, mental health and exposure to repeat violence when they start the trial and 3, 6, and 12-months later.