In the aftermath of the COVID-19 pandemic, more and more people want to be vaccinated to prevent general health problems. In every country, there are health systems, which range from manual to automated systems. In general, private companies develop automated systems that sell software for the health sector. For this reason, it has been decided to develop an open-source web system that facilitates health centers to implement a system to control vaccination processes free of charge. The OSCRUM methodology was used to develop open-source software (OSS). With this methodology, OSS development can be carried out orderly and with a high success rate. OSCRUM facilitates the development of the web-based OSS system called All Vaccinated within the established timeframe. All Vaccinated for the control of vaccination processes is the result of the application of the OSCRUM development methodology. The OSS All Vaccinated web system will benefit health centers or institutions dedicated to vaccination in the optimization of their processes. It is concluded that choosing a development methodology has dramatically facilitated the construction processes for an OSS project and opened the door for new users to collaborate in developing the OSS project.