NN-SVG enables machine learning researchers to create neural network diagrams programmatically rather than manually drawing them. It supports three visualization styles: fully-connected neural networks (FCNN), convolutional neural networks (CNN) inspired by LeNet, and deep network figures following the AlexNet style. The tool uses D3.js for FCNN and CNN rendering and Three.js for deep network visualization, offering extensive customization of size, color, and layout parameters. Generated SVGs are suitable for academic papers, presentations, and web pages.