Abstract. Web browsers are at the core of online user experience, enabling a wide range of Web applications, like communication, games, entertainment, development, etc. Additionally, given the variety and complexity of online-supported tasks, users have started parallelizing and organizing their online browser sessions by employing multiple browser windows and tabs. However, there are few solutions that support analysts and casual users in detecting and extracting patterns from these parallel browsing histories. In this paper we introduce WebComets, an interactive visualization for exploring multi-session multi-user parallel browsing logs. After highlighting visual and functional aspects of the system, we introduce a motif-based contextual search for enabling the filtering and comparison of user navigation patterns. We further highlight the functionality of WebComets with a use case. Our investigations suggest that parallel browser history visualization can o↵er better insight into user tabbed browsing behavior and support the recognition of online navigation patterns.