Using VSCodium with the Open VSX Registry to Avoid Microsoft Marketplace Dependence

Problem: Needed extensions live only in Microsoft’s Marketplace

Many developers choose VSCodium for its fully open‑source build of VS Code, but they still hit a wall when a required extension is published exclusively to the Microsoft Visual Studio Marketplace. That marketplace requires a Microsoft account, sends telemetry, and ties the editor to proprietary services.

Thesis: VSCodium’s bundled Open VSX client lets you install and publish extensions without any Microsoft services

VSCodium ships with the Open VSX Registry pre‑configured, so the same extension API works against a community‑run registry. This gives you the freedom to stay completely open‑source while retaining the familiar VS Code extension experience.

Section 1 – Getting VSCodium ready

1. Download the latest stable .tar.gz or .zip from the VSCodium GitHub releases page.
2. Verify the SHA‑256 checksum shown on the release page (run shasum -a 256 VSCodium‑*.zip and compare).
3. Extract and launch the editor; the Welcome screen already shows the Open VSX icon in the Extensions view (Ctrl+Shift+X).

No extra configuration is needed; the registry URLs are baked into the product.

Section 2 – Installing an extension from Open VSX

Open the Extensions view, search for "Prettier". Results display a small "Open VSX" badge next to each entry, indicating the source is https://open-vsx.org. Click the entry hosted by esbenp and press Install. The extension is fetched directly from the registry and appears alongside built‑in extensions.

To verify the install:

• Open the Developer Tools (Ctrl+Shift+I) and check the console for a log like [prettier] Activated version 8.8.0.
• Compare that version with the one shown on https://open-vsx.org/item/esbenp/prettier; they should match.

Worked example – Publishing a custom language support extension

Assume you have a simple extension folder my-lang with a package.json and the usual src/ tree.

1. Install the Open VSX CLI locally (no admin rights needed): npm i -D @open-vsx/vsce.
2. Create a personal access token on Open VSX and store it securely, e.g. export OPENVSX_TOKEN=abcd1234.
3. From the extension’s root directory run:

   npx @open-vsx/vsce publish --pat $OPENVSX_TOKEN

   This command contacts https://open-vsx.org, uploads the package, and returns a version number.
4. Reload VSCodium (Ctrl+Shift+P → "Reload Window"). The new extension appears in the Extensions view under "Installed" and is ready to use.

Where to run: any terminal with access to the project folder (inside VSCodium’s integrated terminal or an external shell). Required permissions: read/write to the project directory; publishing requires only the token, not elevated system rights. Risks: treat the token like a password—if leaked, anyone could publish under your name. Rotate it if you suspect exposure.

Trade‑off / Limitation

Open VSX hosts fewer extensions than the Microsoft Marketplace. Popular Microsoft‑maintained tools such as Live Share or certain debug adapters may be missing or lag behind. Teams must decide whether the openness gain outweighs the possible feature gap, and may need to maintain duplicate publishing pipelines if they want to reach both audiences.

Practical verification steps

1. Check product.json in the VSCodium installation: confirm "extensionsGallery" contains "https://open-vsx.org/vscode/gallery" and "https://open-vsx.org/vscode/item".
2. In the Extensions view, verify every result shows the Open VSX badge.
3. After installing any extension, compare its version number with the listing on https://open-vsx.org.

Actionable closing

Start by mirroring your essential extensions to Open VSX using the provided GitHub Action (open-vsx-action). Then switch your team’s standard editor to VSCodium, monitor the Open VSX dashboard for update notifications, and consider contributing missing packages back to the community. This approach gives you a fully open‑source editor workflow without sacrificing the ability to install and publish the extensions you rely on.