Abstract
With the expansion of technology, the vending machine has become widespread around the world, as it saves time and effort for the customer and allows them to abandon the old systems that take their time and be complicated. Re-engineering is the examination and alteration of a system to reconstitute it in a new form. Also, the re-engineering process is considered as a software engineering methodology when the existing system needs to the evolution process. This research aims to re-engineer to improve the functionality; risk re-analysis, re-engineer of the requirements, and redesign the functions developments of the vending machine. This research proposes to add some features such as making multiple payment methods available and the ease of replacing, returning the product, and redesigned using the UML diagrams to demonstrate the development processes that are proposed. The development of the vending machine has been reached as it has become easier and more flexible to use and solve the most common problems while providing safety while using them. A questionnaire was conducted for the public to take samples and make suggestions, including adding the feature of replacing the product after leaving the vending machine and their approval rate was 76%, the other feature is sterilizing the products and the result of their support 95.6%, in addition to service to recover the remaining money their approval rate was 94%. And after collecting opinions, it was confirmed that our proposal is useful and appropriate for the development of the vending machine when applied to society to improve the functionality of the system.