In my opinion, the most important feature in a heatmap tool is accurate user interaction tracking and visualization, because the primary goal of a heatmap is to clearly show how users interact with a website through clicks, scrolls, and mouse movements. When this data is captured and visualized accurately, it helps businesses understand user behavior patterns, identify high-engagement areas, and detect sections where users lose interest or face difficulty. This insight is crucial for optimizing page layout, improving navigation, and increasing conversions. While features like segmentation, session recordings, and analytics integration are also valuable, accurate interaction tracking is the foundation because without reliable data, all other insights become misleading or ineffective.