Add and configure extensions

Extensions are reusable bundles that extend Junie CLI with project-specific or domain-specific capabilities. A single extension can package any combination of:

This makes extensions a convenient way to install a curated set of capabilities for a particular technology stack (for example, an Android, Spring Boot, or SQL extension), share team-wide setups, or distribute community-built integrations — without manually configuring each piece.

Run the /extensions slash command (aliases: /plugin, /plugins) to open the extensions screen, where you can browse marketplaces, install, update and remove extensions, and configure additional marketplaces.

Marketplaces

Extensions are distributed via marketplaces. A marketplace is a Git repository that contains a manifest with a list of available extensions and references to where their content is hosted.

Junie CLI supports two marketplace manifest formats:

The native Junie format with .junie-extension/marketplace.json.
The Claude plugin format with .claude-plugin/marketplace.json.

This means you can connect any Claude-compatible plugin marketplace to Junie CLI in addition to Junie's native marketplaces.

Built-in marketplace

Junie CLI ships with the official JetBrains marketplace pre-registered:

https://github.com/JetBrains/junie-extensions

The marketplace contains a curated set of extensions maintained by the Junie team — for example, extensions for Java, Kotlin, Android, Spring Boot, SQL, Redis, and others.

Add a custom marketplace

To register an additional marketplace:

Run /extensions and switch to the Marketplaces tab.
Choose Add marketplace and provide a GitHub repository URL (or owner/repo shorthand, which is expanded to https://github.com/owner/repo).
The repository must contain either a .junie-extension/marketplace.json or a .claude-plugin/marketplace.json file at its root.
Junie CLI clones the repository locally and lists its extensions in the catalog.

To remove a custom marketplace, select it in the Marketplaces tab and choose Remove. The built-in JetBrains marketplace cannot be removed.

You can also drive the same actions inline via /extensions <arg>:

/extensions marketplace add <github-repo-url-or-owner/repo>
/extensions marketplace remove

Install an extension

Run /extensions to open the extensions screen.
Browse the catalog of available extensions across all registered marketplaces, or use search to find a specific extension.
Select an extension and choose the installation scope:
- Project — the extension is enabled only in the current project. The reference is stored in .junie/extensions.json at the root of the project. This file can be checked into version control and shared with the team.
- User — the extension is enabled across all projects on your machine. The reference is stored in ~/.junie/extensions/extensions.json (or %USERPROFILE%\.junie\extensions\extensions.json on Windows).

Extension content (skills, agents, commands, MCP configs, guidelines) is downloaded once into the user-level cache directory ~/.junie/extensions/<marketplace>/<extension>/ and reused across projects.

You can also pass a raw trailing argument directly to the /extensions command, for example:

/extensions install <extension-name>

Newly installed extensions become available within the running session — there is no need to restart Junie CLI.

Remove an extension

To uninstall an extension:

Run /extensions and switch to the Installed tab.
Select the extension and choose Remove.

The reference is removed from the corresponding extensions.json file. Cached content under ~/.junie/extensions/ may be reused if the extension is reinstalled later.

Update an extension

To pull the latest version of an installed extension, select it in the Installed tab and choose Update.

Where extensions are stored

Location	Purpose
`~/.junie/extensions/`	Base directory for cached extension content.
`~/.junie/extensions/extensions.json`	User-scope configuration: extensions enabled for the current user across all projects.
`~/.junie/extensions/marketplaces.json`	Registry for registered marketplace repositories and their sync status.
`.junie/extensions.json`	Project-scope configuration: extensions enabled for the current project; can be committed to VCS.
`~/.junie/extensions/marketplaces/`	Cloned marketplace repositories.

Both extensions.json files share the same format: a flat JSON object that maps a marketplace identifier to the list of installed extensions for that marketplace. For non-built-in marketplaces the GitHub url is also stored, so a teammate who pulls the project can auto-register the marketplace without configuring it manually:

{
  "github-JetBrains-junie-extensions": { "extensions": ["context7"] },
  "github-myorg-myrepo": { "url": "https://github.com/myorg/myrepo", "extensions": ["my-ext"] }
}

You can override the base directory with the following command-line option:

Option	Default	Description
`--extensions-default-location <path>`	`~/.junie/extensions`	Override the default extensions directory. Can also be set via the `JUNIE_EXTENSIONS_DEFAULT_LOCATION` environment variable.

20 May 2026