Domestic violence is a serious problem affecting the health and wellbeing of women globally. Interventions in health care settings have primarily focused on screening and referral, however, women often may not disclose abuse to health practitioners. The internet offers a confidential space in which women can assess the health of their relationships and make a plan for safety and wellbeing for themselves and their children. This randomised controlled trial is testing the effectiveness of a web-based healthy relationship tool and safety decision aid (I-DECIDE). Based broadly on the IRIS trial in the United States, it has been adapted for the Australian context where it is conducted entirely online and uses the Psychosocial Readiness Model as the basis for the intervention.In this two arm, pragmatic randomised controlled trial, women who have experienced abuse or fear of a partner in the previous 6 months will be computer randomised to receive either the I-DECIDE website or a comparator website (basic relationship and safety advice). The intervention includes self-directed reflection exercises on their relationship, danger level, priority setting, and results in an individualised, tailored action plan. Primary self-reported outcomes are: self-efficacy (General Self-Efficacy Scale) immediately after completion, 6 and 12 months post-baseline; and depressive symptoms (Centre for Epidemiologic Studies Depression Scale, Revised, 6 and 12 months post-baseline). Secondary outcomes include mean number of helpful actions for safety and wellbeing, mean level of fear of partner and cost-effectiveness.This fully-automated trial will evaluate a web-based self-information, self-reflection and self-management tool for domestic violence. We hypothesise that the improvement in self-efficacy and mental health will be mediated by increased perceived support and awareness encouraging positive change. If shown to be effective, I-DECIDE could be easily incorporated into the community sector and health care settings, providing an alternative to formal services for women not ready or able to acknowledge abuse and access specialised services.Trial registered on 15(th) December 2014 with the Australian New Zealand Clinical Trials Registry ACTRN12614001306606.