Basic Blue 99 is widely used as a dye in the textile industry for coloring acrylic, nylon, and other synthetic fibers. It is particularly valued for its bright and stable blue shade, making it a popular choice for fabrics requiring vibrant and long-lasting colors. Additionally, it finds application in the paper industry for dyeing paper products, providing consistent and high-quality coloration. In biological staining, Basic Blue 99 is utilized as a histological stain to enhance the visibility of cellular structures under a microscope, aiding in medical and research diagnostics. Its ability to bind effectively to materials ensures reliable performance across various industrial and scientific applications.