> ## Documentation Index
> Fetch the complete documentation index at: https://docs.shipmobilefast.com/llms.txt
> Use this file to discover all available pages before exploring further.

# 4. Build your app

> Build your app

<Steps>
  <Step>
    In the previous step, we created our AI Proxy backend.

    Now we can create a development build on Expo.
  </Step>

  <Step>
    There are two ways to build the app.

    * **Using the prebuild command**
    * **Using the EAS Build**

    <Info>
      I am going to show you both ways but I am going to use the prebuild command.

      Because the fastest way to build the app is using the prebuild command.
    </Info>

    <Warning>
      But eventually, you will need to use the EAS Build to build the app for production.
    </Warning>
  </Step>

  <Step>
    First, open terminal and run the following command:

    <Tabs>
      <Tab title="Prebuild">
        <Steps>
          <Step>
            ```bash theme={null}
            npx expo prebuild
            ```
          </Step>

          <Step>
            ```bash theme={null}
            npx expo run:{platform}
            ```

            <Info>
              Replace `{platform}` with `ios` or `android`.
            </Info>
          </Step>
        </Steps>
      </Tab>

      <Tab title="EAS Build">
        <Steps>
          <Step>
            ```json eas.json (1,3) theme={null}
            "build": {
            "development": {
                "developmentClient": true,
                "distribution": "internal",
                "ios": {
                "simulator": true
                }
              }
            }
            ```
          </Step>

          <Step>
            ```bash theme={null}
            eas login
            ```
          </Step>

          <Step>
            ```bash theme={null}
            eas init
            ```
          </Step>

          <Step>
            ```bash theme={null}
            eas build --profile development --platform {platform}
            ```

            <Info>
              Replace `{platform}` with `ios` or `android`.
            </Info>
          </Step>
        </Steps>
      </Tab>
    </Tabs>
  </Step>

  <Step>
    After the build is finished, you can run the app on your device.
  </Step>

  <Step>
    If you want to run the app on your device, you can use the following command:

    ```bash theme={null}
    npx expo run:{platform} --device
    ```

    <Info>
      Replace `{platform}` with `ios` or `android`.

      Pick a device from the list.
    </Info>
  </Step>

  <Step>
    ### Now how we can deploy our backend on Production?

    <Card title="How to deploy backend to Railway" href="/aiwrapper/deployment" icon="key">
      Click to navigate to the [How to deploy backend to Railway](/aiwrapper/deployment) page.
    </Card>
  </Step>
</Steps>