New technologies emerge with the aim of assisting daily activities and making people's lives easier, but they are subject to exposing a portion of the population to a phenomenon called digital exclusion. Accessibility techniques are some of the ways to combat exclusion by generating digital inclusion. There are several ways to assess accessibility by measuring adherence to techniques. This work presents a heuristic accessibility assessment model for Web software, based on maturity levels and using a multi-criteria classification approach. The study contains a description of how the construction of the maturity model was carried out, as well as its validation. The maturity model created presents four maturity levels and 13 criteria that are based on WCAG 2.2 guidelines. The classification of software resulting from the application of the multi-criteria decision support model presented consistent results and demonstrates the viability of the model in helping professionals and companies that produce software for the Web.