Using Open VSX Registry in VSCodium: What It Means for Your Extensions

Why VSCodium looks different when you search for extensions

When you first open VSCodium, the Extensions view shows a search box that queries the Open VSX Registry instead of the Microsoft Visual Studio Code Marketplace. This change is intentional: the project strips out Microsoft telemetry and replaces the default gallery URL with a community‑run alternative.

Worked example: installing the Python extension

1. Open the Extensions sidebar (Ctrl+Shift+X or Cmd+Shift+X).
2. Type python in the search box.
3. If the extension appears, click Install. VSCodium will download the package from https://open-vsx.org.
4. After installation, open the Settings UI (Ctrl+,) and search for python to confirm the extension is active.

If you do not see the Python extension, it may not yet be published to Open VSX. You can verify the source by opening the Developer Tools (F12) and watching the Network tab while searching; the request URL will start with https://open-vsx.org.

Trade‑offs and limitations

• Extension coverage: Open VSX hosts a subset of the Marketplace. Popular extensions like ms-python.python are usually present, but some Microsoft‑only extensions (e.g., ms-vscode.cpptools when it relies on proprietary download services) may be missing or outdated.
• Update lag: Because VSCodium must reapply its patches to each new VS Code release, there can be a delay of a few days between the upstream release and the corresponding VSCodium build.
• Re‑enabling the Microsoft gallery: You can add the original Marketplace URL back in settings.json, but doing so restores the telemetry endpoints that VSCodium aims to remove.

When to keep the default and when to add the Microsoft gallery

If your primary goal is to avoid any data sent to Microsoft, stay with the Open VSX default and only install extensions that are available there. If you need a specific extension that is absent from Open VSX and you are comfortable with the associated telemetry, add the following to your settings.json:

{
  "extensions gallery": {
    "serviceUrl": "https://marketplace.visualstudio.com/_apis/public/gallery",
    "cacheUrl": "https://vscode.blob.core.windows.net/gallery/index",
    "itemUrl": "https://marketplace.visualstudio.com/items"
  }
}

After saving, restart VSCodium and repeat the extension search; the Network tab will now show requests to visualstudio.com.

Actionable checklist

1. Confirm you are running VSCodium: Help → About shows a build identifier like v1.95.0‑codium.
2. Check the default gallery: open settings.json and verify there is no extensions gallery section, or that it points to open-vsx.org.
3. Try installing an extension you need; watch the Network tab to see which domain is contacted.
4. If the extension is missing, decide whether to add the Microsoft gallery (and accept telemetry) or look for an alternative on Open VSX.