The DESY Engineering Data Management System, DESY EDMS, is a fully Web-based central information management platform at the European XFEL and the Global Design Effort for the International Linear Collider (ILC GDE). It provides functionality for managing documents and 3D CAD data and for performing configuration and change management. It can control complex information structures and keep track of their dependencies and history, i.e. their evolution over time. Due to its powerful capabilities for automating workflows and controlling information access, the DESY EDMS can coordinate processes and manage authorizations and responsibilities in large and complex organizations, which may include several institutes and industrial partners. Applications of the DESY EDMS range from small-scale document management for work groups, up to managing the complexity of world-wide collaborations during design and construction activities. The poster describes the architecture of the DESY EDMS, introduces some of its use cases and reports lessons learned in developing and operating the system.