Currently, cortisol level measurements in the body performed in laboratories typically use the Electrochemiluminescence Immunoassay (ECLIA) method, which requires expensive materials, equipment, and specialized personnel. Researchers have developed a cortisol measurement kit that uses paper as a substrate, which is more cost-effective, and wax ink to delineate the testing area, allowing for customizable test areas. The design features a small test area to reduce the amount of samples needed. This kit still relies on the competitive immunoassay principle and utilizes gold nanoparticles (AuNPs) as signal indicators, which produce a visible color change that can be observed with the naked eye. This makes the kit easy to use, convenient, and applicable for measuring cortisol levels in the body.