---
title: "Start a JSS app in disconnected mode"
slug: "start-a-jss-app-in-disconnected-mode"
abstract: "Develop Sitecore JSS applications without a Sitecore instance"
---
# Start a JSS app in disconnected mode

To develop a JSS application locally without access to a running Sitecore instance, you must start your JSS application in disconnected mode.

> [!important]
> This procedure only applies to JSS applications that fetch data using the REST Layout and Dictionary services. You must follow a different procedure to start the application in disconnected mode when using GraphQL services.

Because you do not have access to a Sitecore instance, you must mock content data using local files using the YAML or JSON formats.

Running a JSS application in disconnected mode is advantageous when developers do not have access to a Sitecore instance, their primary expertise is in JavaScript, or when it would be undesirable for front-end developers to have their own Sitecore instance (technical or business limitations).

> [!important]
> If you plan on working with a Next.js JSS application, you must include the `nextjs-styleguide` add-on when you [create the app](https://doc.sitecore.com/xp/en/developers/hd/20/sitecore-headless-development/the-jss-app-initializer.html "The JSS app initializer"). The add-on is responsible for adding the `data` and `sitecore/definitions` folders required for running the app in disconnected mode.

The following diagram shows the flow of requests from the application to the data files.

![Request flow in JSS disconnected mode](https://doc.sitecore.com/api/markdown-image/xp/en/developers/hd/20/sitecore-headless-development/images/ApplicationModesDisconnected16_.svg)

Developers can [import applications](https://doc.sitecore.com/xp/en/developers/hd/20/sitecore-headless-development/jss-app-import-api.html "JSS App Import API") developed in disconnected mode to Sitecore, creating all necessary Sitecore items for the applications to run in connected mode later.

A common development path might be for an application's lifecycle to begin in disconnected mode, and at later development stages transition to [connected mode](https://doc.sitecore.com/xp/en/developers/hd/20/sitecore-headless-development/start-a-jss-app-in-connected-mode.html "Start a JSS app in connected mode") if the [limitations of disconnected import](https://doc.sitecore.com/xp/en/developers/hd/20/sitecore-headless-development/characteristics-of-the-jss-code-first-import-process.html "Characteristics of the JSS code-first import process") need to be circumvented.

> [!tip]
> JSS applications include a script in their `package.json` file to start the application in disconnected mode.

To start the application in disconnected mode:

1. In a terminal, navigate to your JSS application folder and run the following script:

    ```shell
    jss start
    ```

    The script starts the local development server.

2. In your browser, open `http://localhost:3000` if it does not open automatically.