The CLI `dev` command allows the Trigger.dev service to send messages to your site. This is required for registering Jobs, triggering them and running tasks. To achieve this it creates a tunnel (using [ngrok](https://ngrok.com/)) so Trigger.dev can send messages to your machine.

You should leave the `dev` command running when you're developing.

In a **new terminal window or tab** run:

<CodeGroup>

```bash npm
npx @trigger.dev/cli@latest dev
```

```bash pnpm
pnpm dlx @trigger.dev/cli@latest dev
```

```bash yarn
yarn dlx @trigger.dev/cli@latest dev
```

</CodeGroup>
<br />
<Note>
  You can optionally pass the port if you're not running on the default port by adding
  `--port 3001` to the end.
</Note>