Analyzing complex 3D image data is essential across many research fields, but existing tools are often slow, difficult to use, and limited in flexibility. Our solution, nnInteractive, makes this process simple and efficient by allowing users to interact with images using intuitive actions like clicks, scribbles, boxes, or freehand selections. While the user works in 2D, the system automatically generates precise full 3D segmentations in the background. It is designed to work across a wide range of data types, including medical imaging, microscopy, and other volumetric datasets, making it highly versatile for different research applications. Unlike many current solutions, nnInteractive is directly integrated into commonly used visualization and analysis software, eliminating the need for complex or restrictive web-based tools. This enables faster analysis, improved accuracy, and smoother workflows, bringing advanced AI-powered 3D segmentation into everyday research environments.