N-Formylsaccharin is primarily used in organic synthesis as a versatile reagent. It serves as a formylating agent, enabling the introduction of formyl groups into various organic compounds. This is particularly useful in the preparation of pharmaceuticals, where formyl groups are often key functional groups in active drug molecules. Additionally, it is employed in the synthesis of heterocyclic compounds, which are important in the development of agrochemicals and dyes. Its stability and reactivity make it a valuable tool in research and industrial applications for constructing complex molecular structures.