Plain Customers API
Create, update, fetch, and manage customers and customer groups via GraphQL. Idempotent upsertCustomer with onCreate / onUpdate semantics keyed on an external id or email, plus customer events and spam controls.
Documentation
Documentation
https://www.plain.com/docs/api-reference/graphql/customers/upserting-customers
APIReference
https://www.plain.com/docs/api-reference/graphql/introduction