Sign-in from a backend service on behalf of a consumer customer (B2C) or customer delegate (B2B). Used by custom integrations and e-commerce plugins as a form of single-sign-on for the checkout. If the customer has been authenticated with the merchant's website, this lets them also authenticate a known customer with April. This is a pre-requisite for using the checkout for a B2B customer.

For both B2B and B2C customers having an authenticated session with the checkout also unlocks access to saved cards as a payment source.

Note merchants need to have been registered as supporting B2B customer when onboarded to be able to support B2B customers in the checkout.