Eclipse Theia is an open source platform for building web- and cloud-based tools and IDEs. Possible use cases range from providing custom language support, DSLs, but also graphical modeling tools and data-centric configuration UIs. Theia provides a workbench, a module system and reusable base features such as Git integration. Theia-based tools can be deployed remotely and accessed via a browser, or as an alternative, as a desktop Application (via Electron). Theia is based on Typescript, HTML, CSS, the Language Server Protocol (LSP) and Monaco Code editor provided by VS Code. Find more details in this introduction of Eclipse Theia.