Web design is a complex and challenging task. It involves making many design decisions that materialise preconceived notions of user needs that may or may not be true. In this paper, we investigate supporting the co-design of a website with visual feedback elicited from the website’s community of users. Website users can express their needs by re-arranging and modifying the website’s layout and design. To explore and validate this idea, we present CrowdUI, a web-based tool that enables members of the community of a website to visually express their design improvement ideas, frustrations and needs, and to send this feedback to the person in charge of designing or maintaining the website.CrowdUI is validated in a study with 45 users of a popular social media and networking website. Second, our qualitative evaluation with 60 experienced web developers shows that CrowdUI is able to elicit diverse and meaningful feedback. Put together, our results suggest that CrowdUI’s approach constitutes a productive setting for eliciting visual feedback from the user community as a complement to traditional ways of eliciting feedback and participatory design. Finally, based on our experiences, we discuss a design space for crowdsourced web design and provide design recommendations for similar future tools.