> For the complete documentation index, see [llms.txt](https://codex-editor.gitbook.io/project-accelerate/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://codex-editor.gitbook.io/project-accelerate/development/codex-basics/extensions.md).

# Extensions

Codex uses extensions and extension packs to deliver specific functionality to users for various types of translation [Projects](/project-accelerate/development/codex-basics/projects.md). 

In general, developer questions are best answered using the [official VS Code Extension API](https://code.visualstudio.com/api), which includes API details, tutorials, UX/UI guidelines, and more. 

### How do I use an extension?

Do use an existing extension, open your Codex app (or branded instance, like Scribe), and either click on the "Extensions" tab in the activity bar, or else type in `command + shift + p` and then search for "extensions"

<figure><img src="https://4219285846-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FCrkjWLsYWix5ZOP9QKP1%2Fuploads%2FyB95FW3bIqmqoPsRYDFN%2FScreenshot%202024-03-04%20at%2011.53.21%E2%80%AFAM.png?alt=media&amp;token=3fe8c1e8-b18b-4e2f-8136-b4a199811add" alt=""><figcaption><p>You can install extensions from the marketplace, or else you can install a compiled extension (a .vsix file) directly.</p></figcaption></figure>

### How do I build an extension?

There are three kinds of extensions you can build:&#x20;

1. [Language Servers](/project-accelerate/development/codex-basics/extensions/language-servers.md) and Language Support: *Perform background processing on your content, giving diagnostics and updating the content.*
2. Web views (or [Rendered Views](/project-accelerate/development/codex-basics/extensions/rendered-views.md)): *Embed any arbitrary web app inside of Codex.*
3. Custom Editors (e.g., [Custom Notebooks](/project-accelerate/development/codex-basics/extensions/custom-notebooks.md)): *Create a custom editor for one or more specified file types.*