Overlay Tools as a Support for Accessible Websites - Possibilities and Limitations.

Current laws and directives such as the Americans with Disabilities Act and the European Union's Directive 2016/2102 aim to support people with disabilities. At the same time, they also represent a challenge for many website owners who have to comply with these legal requirements. Providers of so-called overlay tools offer, among other things, fully automated solutions which, according to their own statements, can be installed within a few minutes and subsequently improve the website in such a way that it is accessible and compliant with the laws and standards. This raises two questions. First, to what extent overlay tools provide real accessibility improvements? And second, is it possible to identify possibilities and limitations and therefore suggest potential improvements. Based on a comparison of the features of nine existing tools, three were selected for closer examination (accessiBe, EqualWeb and UserWay). In addition, a comparative study of these providers was conducted. For this purpose, a total of seven metrics were defined, which are based on the information and promises of the providers as well as on the requirements of the Web Content Accessibility Guidelines 2.1. To validate the changes made by the overlay tools, the adaptations were evaluated using 29 of the 92 test steps of the BIK BITV-Test. Moreover, the site owner's perspective was taken into account and the corresponding features and functions were analyzed and evaluated within four metrics. However, user tests are not part of this work. Significant differences between the overlay tools can be seen primarily in the adjustments to the actual website. In comparison, accessiBe corrects more failures and barriers for blind users and users who use the keyboard navigation and thus also achieves the best result in the overall score. Despite these improvements, full compliance is clearly not possible. However, both theoretical and concrete opportunities for improvement were identified.