This paper introduces the platform Social4all. The main idea of this research is offering a new approach that allows solving a significant set of Web accessibility problems. So far, website developers have been the only ones responsible for accessibility in websites. In a great number of web pages, issues related to accessibility have been ignored for different reasons, causing browsing problems to those who need accessible web sites. With the proposed platform, the aim is to allow the creation of alternative and more accessible versions of websites by people who are not the owners of them. The generated versions are based on the original site, which is adapted applying a series of semiautomatic adaptations guided by an algorithm and a human assistant. A quantitative evaluation has been done by using Web accessibility evaluation tools. Results of this evaluation show that the platform is useful to detect and solve accessibility problems.