Many users with cognitive or neurodivergent conditions encounter significant barriers when interacting with standard web interfaces, often leading to stress, confusion, and premature task abandonment. This thesis presents the design, development, and evaluation of a browser extension aimed at reducing cognitive load and enhancing web accessibility for these user populations. The tool was conceived as an all-in-one, lightweight solution, integrating several accessibility-focused features including content simplification, key concept highlighting, text summarization, and adaptive navigation aids. The design process followed a modified User-Centered Design (UCD) methodology, adapted to accommodate the needs and participation constraints of users with cognitive impairments. User insights were collected through a qualitative questionnaire, which suggested the selection of core functionalities.