Deceptive interface design, often referred to as dark patterns, can challenge users' ability to make informed choices online. This thesis explores how a browser tool can be designed to detect and present dark patterns in a way that supports user understanding and awareness. The goal was not only to highlight manipulative elements, but also to help users interpret them and respond more critically to deceptive practices. The project was conducted using a Research through Design (RtD) approach, combined with participatory design methods. The design process involved early conceptual work, a participatory workshop, a structured design sprint, and an evaluation workshop with users. Feedback from these phases guided the development of a prototype focused on explanation and interaction design rather than technical detection. The result is a browser tool prototype that combines visual highlights, tooltips, and explanations to make manipulative design patterns more transparent. Key design considerations included clarity, user control, and the balance between simplicity and detail. The findings suggest that explanation strategies, rather than just relying on backend automation or silent blocking, can play an important role in helping users navigate and understand deceptive design. While the prototype does not include working detection functionality, the research contributes insight into how interaction design can support user awareness of dark patterns. The thesis also outlines future directions for development and evaluation, including possibilities for customization and regulatory efforts such as the GDPR. Masteroppgave i informasjonsvitenskap INFO390 MASV-INFO