The RadOnc Toolbox app is a resource that compiles and categorizes both acute and late radiation symptom management strategies and prioritizes them by effectiveness and the levels of evidence that support them. The RadOnc Toolbox app includes: • Evidence-based interventions for managing and preventing 8 of the most common radiation-related toxicities. • Toxicity scales. • Dose constraints. • A dose conversion calculator. • Performance status scales. Toxicities due to radiation therapy are a major source of treatment interruption and cessation and impact patients’ quality of life. Strategies to mitigate these symptoms or potentially prevent them are critical to the optimal management of these patients. The RadOnc Toolbox is designed to be a step towards identifying the best practices in supportive care for patients.