Paint Tool SAI is a lightweight digital painting software developed by Systemax. It is popular among artists for its user-friendly interface and powerful features, making it suitable for both beginners and professionals. The program supports various brush types, layers, and blending modes, allowing for detailed artwork creation. One of the standout features of Paint Tool SAI is its smooth and responsive brush engine, which provides a natural painting experience. Additionally, it supports high-resolution canvases and offers tools for line art, coloring, and shading, making it a versatile choice for digital illustrators and graphic designers.