By conducting a comparative study of two CAT tools, SDL Trados Studio 2017 and MemoQ v8.7, this research project aimed to examine the impact of these tools on the achievement of accessibility conformance during the web localisation process. Two different approaches were adopted to investigate this matter. The first stage comprised a descriptive approach, in which the researcher analysed the CAT tools' performance and determined whether they could support and transfer a selection of qualities related to accessibility embedded in an HTML5 code. The results indicated that the two systems supported and transferred the majority of these elements, but not all of them. The second stage of the research consisted of a tool evaluation carried out by ten novice web localisers. The goal was to measure the functional suitability of the CAT tools and analyse the influence of participants' knowledge of accessibility on the final target product.