When developing apps with [`shopify app dev`](/docs/api/shopify-cli/app/app-dev), you have multiple options for connecting your local development server to Shopify:

- [Cloudflare Quick Tunnels](#cloudflare-quick-tunnels) (default)
- [Localhost-based development](#localhost-based-development)
- [Bring your own tunnel](#bring-your-own-tunnel) (such as ngrok)

Choose the option that best fits your development needs and environment.

## Cloudflare Quick Tunnels

By default, Shopify uses [Cloudflare Quick Tunnels](https://developers.cloudflare.com/cloudflare-one/connections/connect-networks/do-more-with-tunnels/trycloudflare/) to open a publicly accessible tunnel to your app. Tunneling provides a secure (HTTPS) URL to your local environment.

> Tip:
> If you're experiencing connectivity errors with Cloudflare Quick Tunnels, refer to [Cloudflare guidance](https://developers.cloudflare.com/cloudflare-one/connections/connect-networks/configure-tunnels/tunnel-with-firewall/) on firewall requirements, or try one of the alternatives in this guide.

## Localhost-based development

When using [Shopify CLI ](/docs/api/shopify-cli) version `3.80` or higher, passing the [`--use-localhost` argument](/docs/api/shopify-cli/app/app-dev#flags-propertydetail-uselocalhost) serves your app using `localhost` (`127.0.0.1`) with a self-signed HTTPS certificate. Shopify CLI creates this certificate for you using [`mkcert`](https://github.com/FiloSottile/mkcert).

To serve your app using `localhost`, run the following command:

    
    ```bash
    shopify app dev --use-localhost
    ```

    

Shopify CLI runs a reverse proxy server on port `3458` which forwards to your app. You can override this port by passing the [`--localhost-port`](/docs/api/shopify-cli/app/app-dev#flags-propertydetail-localhostport).

> Note:
> Localhost-based development isn't compatible with the Shopify features that directly invoke your app, such as [Webhooks](/docs/apps/build/webhooks), [App proxy](/docs/apps/build/online-store/display-dynamic-data), and [Flow actions](/docs/apps/build/flow/actions), and features that require you to test your app from another device, such as [POS](/docs/apps/build/pos).

### Localhost-based development with Windows Subsystem for Linux (WSL)

When you run the [`shopify app dev`](/docs/api/shopify-cli/app/app-dev) command on WSL, `mkcert` installs the HTTPS root certificate in the Linux environment, but not in Windows. This results in certificate errors when you attempt to preview your app in a Windows-based browser.

To install the certificate in Windows, do the following. This is only needed the first time you run an app with `--use-localhost`.

1. In a WSL terminal, navigate to your app's directory.
1. Run the following command:

    
    ```bash
    certutil.exe -user -addstore root "$(wslpath -w "$(./.shopify/mkcert -CAROOT)/rootCA.pem")"
    ```

    

#### Manual certificate installation

If you've disabled Windows interop or Windows `PATH` in WSL, then you can manually install the certificate with the following steps:

1. In an Explorer window, navigate to `\\wsl.localhost\<distribution>\usr\local\share\ca-certificates`.
    - For example, `\\wsl.localhost\Ubuntu\usr\local\share\ca-certificates`
1. Double click on the `mkcert_development_CA` certificate file found at this path.
1. Click **Open**
1. Select **Local Machine** and click **Next**.
1. Select **Place all certificates in the following store**.
1. Click **Browse**.
1. Select **Trusted Root Certification Authorities**.
1. Click **Next** and **Finish**.

## Bring your own tunnel

The [`--tunnel-url` argument](/docs/api/shopify-cli/app/app-dev#flags-propertydetail-tunnelurlvalue) allows you to specify the URL of an alternate network tunnel to your app. You can use this argument with [ngrok](https://ngrok.com/) with the following steps:

1. Set up an [ngrok](https://ngrok.com/) account.
1. Install the [ngrok CLI](https://ngrok.com/download).
1. Follow the steps in the ngrok documentation to [set up your access token](https://ngrok.com/docs/agent/#authtokens).
1. In a terminal, start ngrok using the following command. You can alternatively choose another port number.

    
    ```sh
    ngrok http 3000
    ```

    

1. Note the URL ending in `ngrok-free.app` that's returned - you'll need this URL in the following command - and leave ngrok running.
1. Run `app dev` using the `--tunnel-url` argument. If you've chosen another port number, then use that instead.

    
    ```sh
    shopify app dev --tunnel-url=https://<ngrok-URL>:3000
    ```