In this paper, we present bcode, a lightweight, browser-based collaborative code editor designed to support small-group learning in both in-person and virtual CS1 courses. Whereas most collaborative IDEs in the literature are built for enterprise contexts, bcode draws on research in collaborative and peer-based learning. The platform facilitates real-time, multi-user editing by providing instructors “rooms” in which “groups” of students coauthor code, allowing structured collaboration. The contents of each group are visible to the instructors at all times, enabling live oversight and just-in-time teaching. The platform can also provide LLM-generated hints to help students get unstuck. bcode’s design centers on accessibility for students and instructors: only a short alphanumeric code is required to join a room, and the platform runs Python, C++, and graphics code entirely within the browser using WebAssembly, eliminating the cost of server infrastructure.

We deployed bcode in two large-scale educational contexts: an in-person CS1/CS2 teaching assistant program at our R1 institution and two global offerings of a CS1 MOOC whose combined enrollment exceeded 30,000. Instructors voluntarily adopted the tool, and we observed high engagement across both deployments, with a regression analysis suggesting bcode correlates with increased student participation at a marginal significance. Our evidence also suggests that the flexibility of the room and group system made bcode adaptable to a range of teaching formats, including in-person and remote. We discuss design lessons from observed usage patterns and outline future directions, including additional features supporting collaborative pedagogy and follow-up studies to assess causal impacts on participation.