Eclipse Theia

Last reviewed Aug 26, 2026 · 808 words

If what you want is VS Code in a browser tab on your own server, install code-server and stop reading; that is what most people who search for Theia are actually after. Eclipse Theia answers a narrower question: a VS Code-compatible IDE that Microsoft does not control, governed by the Eclipse Foundation under EPL-2.0, and built so that you (or Arduino, or a company shipping an internal developer tool) can strip it down and release your own editor. There is a ready-made product called Theia IDE for people who just want to use it, and it is decent, but the reason the project exists is the platform underneath.

Theia the platform and Theia IDE the product are different things

The catalogue's description, "extensible platform for building cloud and desktop IDEs," is the accurate one. Theia is a set of TypeScript packages that give you an editor shell, a file explorer, terminals, debug adapters, language server support and a plugin host, with every piece replaceable. Arduino IDE 2 is a Theia application; you would not know from using it. Theia IDE is the Eclipse Foundation's own assembly of those packages into something that looks and feels like VS Code, available as a desktop download for Windows, macOS and Linux and as a Docker image for the browser.

For a self-hoster the split matters because the platform is the part with 21,655 stars and active governance, and the IDE is a reference build that gets less love than code-server's daily-driver polish.

Extensions come from Open VSX, and code-server has the same problem

Microsoft's extension marketplace terms restrict it to Microsoft's own products, so Theia (like code-server) pulls extensions from Open VSX, the Eclipse-run alternative registry. Most popular open-source extensions are there. The ones that are not are the proprietary Microsoft ones: Pylance, the C# DevKit, Remote Development, Live Share and GitHub Copilot. If your workflow depends on any of those, neither Theia nor code-server will give it to you, and the honest alternative is GitHub Codespaces or VS Code's own remote tunnels.

Where Theia has an edge is that its extension API is a superset: it runs VS Code extensions in a plugin host and also supports its own deeper "Theia extensions" that can change the shell itself, which is how the Arduino build removes half the UI.

Running Theia IDE in Docker, and why it must not face the internet

services:
  theia:
    image: ghcr.io/eclipse-theia/theia-ide/theia-ide:latest
    ports:
      - "127.0.0.1:3000:3000"
    volumes:
      - ./project:/home/project:cached
    restart: unless-stopped

The image serves on port 3000 and mounts your working tree at /home/project. It has no authentication of its own; anyone who reaches the port has a terminal as the container user. Bind it to localhost as above and reach it over Tailscale, or put an authenticating proxy such as Authelia in front. The catalogue's 1 GB minimum holds for the editor alone; language servers for TypeScript or Rust routinely add 500 MB to 1 GB each, so size the box for the languages you write, not for Theia.

Recent Theia IDE releases also include an AI assistant layer that can be pointed at a local model server rather than a hosted API, which is a genuine differentiator for people who want editor AI without sending code to a vendor; check the current release notes for which providers are wired up.

Where Theia loses, honestly

The ecosystem is smaller than VS Code's, updates lag VS Code's feature cadence, and the community answering questions is a fraction of the size. Documentation is written for people building IDEs, so a user hitting a configuration issue reads architecture docs to find a setting. The catalogue's difficulty rating of Medium is about that gap, not about Docker. If you want to write code today with the least friction, Coder or code-server on the same box will feel more finished. The editor category lists the rest.

What I'd do

For a personal browser IDE: code-server, behind Tailscale, done. Choose Theia IDE when vendor neutrality is a real requirement (a regulated workplace, a company policy against Microsoft-controlled tooling, or a preference for foundation governance), and expect to trade a little polish for it. Choose Theia the platform when you are building an editor for other people, a teaching environment with a locked-down UI or a domain-specific tool, because nothing else open-source gives you a VS Code-grade shell you are allowed to gut. In every case bind to localhost, front it with real authentication, and budget RAM for language servers rather than the editor.