Devly, a multi-service development environment Writing a system alone is hard. Building many systems with many people is harder. As our company has grown, we tried many approaches to user-friendly, shared development environments and learned what works and what doesn't. We incorporated what we learned into a tool called devly. Devly is used to develop products at Fastly that span many services written in different languages. We learned that the design of our tools must be guided by how teams work and communicate. To respond to these needs, Devly allows self-service, control, and safety so that developers can focus on their work.