The Eclipse Theia Platform is a free and open-source framework for building IDEs and tools based on web technologies.

[11][12] While Eclipse Theia incorporates certain components from Visual Studio Code, such as the Monaco editor, it is independently developed with a modular architecture and is not a fork of VS Code.

[13][14] Theia was originally developed by TypeFox and Ericsson, and continually receives contributions from EclipseSource, Red Hat, IBM, Google, Arm Holdings as well as from individual contributors.

All of Theia's features are implemented as extensions, which allows third-party developers to modify Theia's functionality by using the same application programming interfaces (APIs) as the application's default components.

[24] In January 2019, JAXenter, a website and blog about coding,[44] ranked Theia as the third-most popular JavaScript integrated development environment of 2018 according to GitHub metrics, behind Visual Studio Code and Atom.