1. [Associate your app registration with the user flow](../external-id/customers/how-to-user-flow-add-application.md).
1. For sign-in flow, [register a customer user](../external-id/customers/how-to-manage-customer-accounts.md#create-a-customer-account), which you use to test the sign-in API. Alternatively, you can get this test user after you run the sign-up flow.
1. For SSPR flow, [enable self-service password reset](../external-id/customers/how-to-enable-password-reset-customers.md) for customer users in the external tenant. SSPR is available for customer users who use email with password authentication method.
[!INCLUDE [entra-external-id-continuation-token](./includes/native-auth-api/continuation-token.md)]
## Sign-up API reference
To complete a user sign-up flow for either authentication method, your app interacts with four endpoints, `/signup/v1.0/start`, `/signup/v1.0/challenge`, `/signup/v1.0/continue`, and `/token`.
### Sign-up API endpoints
| Endpoint | Description |
|-----------------------|--------------------------------------------|
[!INCLUDE [native-auth-api-cors-note](./includes/native-auth-api/user-attribute-format.md)]
1. [Associate your app registration with the user flow](../external-id/customers/how-to-user-flow-add-application.md).
1. For sign-in flow, [register a customer user](../external-id/customers/how-to-manage-customer-accounts.md#create-a-customer-account), which you use to test the flow. Alternatively, you can get this test user after you run the sign-up flow.
1. For SSPR flow, [enable self-service password reset](../external-id/customers/how-to-enable-password-reset-customers.md) for customer users in the external tenant. SSPR is available for customer users who use email with password authentication method.
[!INCLUDE [entra-external-id-continuation-token](./includes/native-auth-api/continuation-token.md)]
## API reference for sign-up
To complete a user sign-up flow for either authentication method, your app interacts with four endpoints, `/signup/v1.0/start`, `/signup/v1.0/challenge`, `/signup/v1.0/continue`, and `/token`.
### API endpoints for sign-up
| Endpoint | Description |
|-----------------------|--------------------------------------------|
[!INCLUDE [native-auth-api-cors-note](./includes/native-auth-api/user-attribute-format.md)]