# Start a sign-in (service picker)
URL: https://musicapi.com/docs/reference/start-sign-in.md

`GET https://app.musicapi.com/{slug}`

Section: Connect your users.
Product: MusicAPI Core and MusicAPI Managed Transfers.
Auth: none. This is a page for the user’s browser, not a JSON call.

A page, not a JSON call. Send the user's browser here. The user picks one of the services you turned on, signs in, and comes back to `returnUrl` with the result (see "Handle the callback").

## Path parameters

| Name | Type | Required | Description |
| --- | --- | --- | --- |
| `slug` | string | yes | Your account slug (Dashboard, Settings). |

## Query parameters

| Name | Type | Required | Description |
| --- | --- | --- | --- |
| `returnUrl` | uri | yes | Where the user comes back to. It must be one of your Return URLs (Dashboard, Settings). |
| `requestOneTimeToken` | boolean | no | Add a one-time token to the callback. With it, your backend or app reads the raw service tokens once. Default: `false`. |
| `uniqueId` | uuid | no | A UUID v4 that you make. Poll `GET /app/integrations/byUniqueId/{uniqueId}` with it. |
| `forwardFailures` | boolean | no | Send the user back to `returnUrl` at once when the sign-in fails. Default: `false`. |
| `merchantUserId` | string | no | Your own id for this user. It is stored on the connected user and in the usage data. |

## Response 200

The service picker page (HTML).

## Example

Send the user’s browser to:

```text
https://app.musicapi.com/{slug}?returnUrl={returnUrl}
```