Widely used as a color-forming agent in carbonless copy paper (also known as pressure-sensitive paper), Crystal Violet lactone enables instant document duplication without the need for carbon sheets. When pressure is applied—such as during writing or typing—the compound reacts with a developer material (like bisphenol A or acidic clay) to produce an intense blue or purple mark. This application is common in forms, invoices, receipts, and multi-part documents.

It is also employed in thermal paper formulations, where heat triggers the color change, making it useful in fax machines, point-of-sale receipts, and labels. Additionally, Crystal Violet lactone serves as a pH indicator due to its color shift in response to acidity, and finds use in some dye-based imaging systems and security inks. Its leuco form allows for reversible or hidden marking in specialty applications such as authentication and tamper-evident materials.