> ## Documentation Index > Fetch the complete documentation index at: https://docs.streamlinedpayments.com/llms.txt > Use this file to discover all available pages before exploring further. # Create customer > Creates a new customer. If you also sell through Shopify, send the buyer's Shopify customer ID as `shopify_customer_id`. When that buyer's Shopify orders sync, they attach to this customer instead of creating a new one. Set it before the buyer's first Shopify order syncs. If a customer already has that Shopify customer ID, you get that customer back with a `200` and nothing is created or changed. So it's safe to send the same create twice. ## OpenAPI ````yaml /api-reference/openapi.yaml post /customers openapi: 3.0.3 info: title: Streamlined API description: > Access customers, customer applications, customer groups, products, payouts, invoices, transactions, and deposit links programmatically through this API, and receive webhooks when deposit links change. All requests must be authenticated with an API key. version: 1.6.0 license: name: Proprietary url: https://streamlinedpayments.com/terms servers: - url: https://api.staging.streamlinedpayments.com/api/v1 description: Sandbox - url: https://api.streamlinedpayments.com/api/v1 description: Production security: - AppIdAuth: [] ApiKeyAuth: [] tags: - name: Customers description: Create, update and delete the businesses you sell to. - name: Customer applications description: >- List the applications your customers submit, and approve them. Approving can also set net terms and export the customer to Shopify. See [Approve customer applications](/guides/customer-applications). - name: Customer groups description: >- Organize customers into groups and manage who's in each one. A group can be linked to a Shopify B2B company. - name: Customer files description: Upload and manage files attached to a customer. - name: Customer addresses description: Manage a customer's addresses and choose their default billing address. - name: Orders description: Create orders, add and remove line items, and schedule them. - name: Invoices description: Create invoices from orders, then list, look up and update them. - name: Transactions description: List transactions and look one up. - name: Payouts description: List payouts, including pending ones, and look one up. - name: Products description: >- Create and update the products and services you sell, import them in bulk, and merge duplicates. - name: Deposit links description: Collect money from a customer before an invoice exists. - name: Webhooks description: >- Register HTTPS endpoints to receive events when something changes. See [Webhooks](/guides/webhooks) for signatures, retries and delivery guarantees. paths: /customers: post: tags: - Customers summary: Create customer description: > Creates a new customer. If you also sell through Shopify, send the buyer's Shopify customer ID as `shopify_customer_id`. When that buyer's Shopify orders sync, they attach to this customer instead of creating a new one. Set it before the buyer's first Shopify order syncs. If a customer already has that Shopify customer ID, you get that customer back with a `200` and nothing is created or changed. So it's safe to send the same create twice. operationId: createCustomer requestBody: required: true content: application/json: schema: type: object required: - customer properties: customer: type: object properties: first_name: type: string description: First name of the customer last_name: type: string description: Last name of the customer company_name: type: string description: Company name of the customer website: type: string description: Website of the customer tags: type: string description: Tags for the customer (comma-separated) tax_exempt: type: boolean description: Whether the customer is tax exempt net_terms: type: integer nullable: true enum: - 0 - 7 - 10 - 15 - 30 - 45 - 60 - 90 description: > Payment terms in days. 0 = Due on receipt. null = inherit from customer group, then merchant default. Only the listed values are accepted. customer_group_uuid: type: string format: uuid nullable: true description: >- UUID of the customer group to associate this customer with. null removes from any group. shopify_customer_id: type: string description: > The buyer's Shopify customer ID, as a number (`1234567890`) or a GID (`gid://shopify/Customer/1234567890`). Stored and returned as a GID. example: '1234567890' shopify_shop_domain: type: string description: > The Shopify store the customer belongs to, like `your-store` or `your-store.myshopify.com`. Required when more than one Shopify store is connected to your account. Only used with `shopify_customer_id`. example: your-store addresses_attributes: type: array items: type: object properties: address1: type: string description: First line of the address address2: type: string description: Second line of the address city: type: string description: City state: type: string description: State or province postal_code: type: string description: Postal code country: type: string description: Country email: type: string format: email description: Email address cc_email: type: string format: email description: CC email addresses (comma-separated list) phone: type: string description: Phone number first_name: type: string description: First name for the address last_name: type: string description: Last name for the address company_name: type: string description: Company name for the address responses: '200': description: >- A customer already has this `shopify_customer_id`. That customer is returned unchanged. content: application/json: schema: $ref: '#/components/schemas/CustomerDetail' '201': description: Customer created successfully content: application/json: schema: $ref: '#/components/schemas/CustomerDetail' '400': description: Bad request content: application/json: schema: $ref: '#/components/schemas/Error' '401': $ref: '#/components/responses/Unauthorized' '422': description: > Unprocessable entity. For `shopify_customer_id` this means the ID isn't a Shopify customer ID, the store isn't connected, `shopify_shop_domain` is missing when you have more than one store, or the ID belongs to a deleted customer. content: application/json: schema: type: object properties: errors: type: array items: type: string components: schemas: CustomerDetail: type: object properties: customer: type: object properties: website: type: string company_name: type: string created_at: type: string format: date-time updated_at: type: string format: date-time tags: type: array items: type: string first_name: type: string last_name: type: string uuid: type: string format: uuid display_name: type: string customer_email: type: string total_open_balance_amount: type: integer quick_pay_enabled: type: boolean average_days_to_pay: type: integer net_terms: type: integer nullable: true enum: - 0 - 7 - 10 - 15 - 30 - 45 - 60 - 90 description: >- Payment terms in days. null means inherit from customer group, then merchant default. net_terms_label: type: string nullable: true description: >- Human-readable label for net_terms (e.g. "Net 30", "Due on receipt"). shopify_customer_id: type: string nullable: true description: >- The Shopify customer this customer is linked to, as a GID. null if not linked. example: gid://shopify/Customer/1234567890 shopify_shop_domain: type: string nullable: true description: >- The Shopify store the linked Shopify customer belongs to. null if not linked. example: your-store application_submitted_at: type: string format: date-time nullable: true description: null if the customer never applied. application_approved_at: type: string format: date-time nullable: true description: null until the application is approved. customer_group: type: object nullable: true description: The group this customer belongs to, if any. properties: uuid: type: string format: uuid company_name: type: string billing_address: $ref: '#/components/schemas/Address' addresses: type: array items: $ref: '#/components/schemas/Address' Error: type: object properties: error: type: string message: type: string Address: type: object properties: id: type: integer address1: type: string address2: type: string city: type: string state: type: string postal_code: type: string phone: type: string country: type: string email: type: string cc_email: type: string description: CC email addresses (comma-separated list) first_name: type: string last_name: type: string company_name: type: string responses: Unauthorized: description: Authentication failed content: application/json: schema: $ref: '#/components/schemas/Error' examples: AuthenticationRequired: value: error: Authentication required message: >- API endpoint requires authentication. Please provide valid X-App-Id and X-Api-Key headers. InvalidCredentials: value: error: Invalid credentials message: >- The provided API credentials are invalid. Please check your X-App-Id and X-Api-Key values. securitySchemes: AppIdAuth: type: apiKey in: header name: X-App-Id description: App ID for authentication ApiKeyAuth: type: apiKey in: header name: X-Api-Key description: API Key for authentication ```` This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.