The Epsilon Playground https://www.eclipse.org/epsilon/live/ is described in its own LR, MDE with the Epsilon Framework.
Eclipse Theia https://theia-ide.org/ is not a modelling tool but a platform for building modelling tools, which can be run on the desktop and in the cloud via a web browser. It supports textual domain-specific modelling languages, for example those developed with Xtext.
Modelix is a project aiming to make MPS available through the web. MPSServer together with WebEditKit are an alternative project trying to move MPS to the cloud.