To build an intermittent fasting app like Zero for icore.sg, start by defining user needs: track fasting schedules, provide customizable reminders, and offer insightful progress analytics. Design a clean, intuitive interface to enhance user experience. Integrate features like goal-setting, fasting history, and educational content on fasting benefits. Use data encryption to protect user privacy and ensure seamless synchronization across devices. Incorporate a social element for community support and motivation. Regularly update the app with user feedback to refine functionality and stay relevant. Finally, test thoroughly to ensure reliability and user satisfaction.