> ## Documentation Index > Fetch the complete documentation index at: https://documentation.suby.fi/llms.txt > Use this file to discover all available pages before exploring further. # Create (or get) a customer > Get-or-create by email. Returns 201 for a new customer, 200 if one with that email already exists. ## OpenAPI ````yaml /v3-beta/api-reference/openapi.yaml post /v3/customers openapi: 3.1.0 info: title: Suby.fi Merchant API version: 3.0.0-beta description: > The **v3** public merchant API for Suby.fi. RESTful (plural, resource-oriented endpoints under the `/v3` prefix). Authenticate every request with your secret API key in the `X-Suby-Api-Key` header. - `sk_live_…` keys operate in **production** (real funds). - `sk_sandbox_…` keys operate in a fully simulated **sandbox** (test cards, Base Sepolia crypto, no real money). The environment is derived from the key prefix. All monetary amounts are **integer cents** (except `priceCents` on some read shapes, which is a string) — token amounts are strings in the smallest unit (sats / lamports / wei). Fees are basis points. contact: email: dev@suby.fi url: https://suby.fi servers: - url: https://api.beta.suby.fi description: Production + sandbox (environment selected by API key prefix) security: - ApiKeyAuth: [] tags: - name: Products description: Manage your product catalog (one-time and recurring). - name: Checkout description: >- Hosted checkout — signed session tokens (`cs_…`) plus branding and appearance settings. - name: Payments description: >- Create, capture, void, and retrieve one-time & off-session payments (card, APM, and crypto). - name: Subscriptions description: Start and cancel recurring subscriptions. - name: Customers description: First-class customer records with billing address. - name: Payment Methods description: >- Save a payment method to a customer and manage saved instruments for off-session charges. - name: Webhook Endpoints description: Register outbound webhook destinations and rotate signing secrets. - name: Analytics description: Org-wide revenue analytics. - name: Health description: Unauthenticated liveness probe. paths: /v3/customers: post: tags: - Customers summary: Create (or get) a customer description: >- Get-or-create by email. Returns 201 for a new customer, 200 if one with that email already exists. operationId: createCustomer parameters: - $ref: '#/components/parameters/IdempotencyKey' requestBody: required: true content: application/json: schema: type: object required: - email description: >- Idempotent get-or-create keyed on `email` (per org + environment) — the same email always resolves to the same customer. properties: email: type: string format: email maxLength: 320 description: Identity key. Required. firstName: type: string maxLength: 100 description: Optional; forwarded to the PSP on card charges. lastName: type: string maxLength: 100 billingAddress: $ref: '#/components/schemas/BillingAddress' description: Optional; drives VAT country + pre-fills future charges. externalRef: type: string maxLength: 120 description: >- Your business reference (CRM/customer id). Stored + echoed + filterable via `?externalRef=`. Not unique. metadata: $ref: '#/components/schemas/Metadata' responses: '200': description: Existing customer returned content: application/json: schema: allOf: - $ref: '#/components/schemas/SuccessEnvelope' - properties: data: $ref: '#/components/schemas/Customer' '201': description: Customer created content: application/json: schema: allOf: - $ref: '#/components/schemas/SuccessEnvelope' - properties: data: $ref: '#/components/schemas/Customer' '401': $ref: '#/components/responses/Unauthorized' '422': $ref: '#/components/responses/ValidationError' components: parameters: IdempotencyKey: name: Idempotency-Key in: header required: false description: >- Optional key (≤255 chars, e.g. a UUID v4) that makes this POST safe to retry: the first request executes and its response is cached for 24h; a retry with the SAME key replays that response instead of re-executing (no duplicate payment/subscription). A reused key with a different request → `422 IDEMPOTENCY_KEY_CONFLICT`; a retry while the first is still in flight → `409`. See the Idempotency guide. schema: type: string maxLength: 255 example: 5f3b9c2e-1a4d-4f2b-9c31-7e2a1b6d8c04 schemas: BillingAddress: type: object properties: line1: type: string maxLength: 200 nullable: true line2: type: string maxLength: 200 nullable: true city: type: string maxLength: 120 nullable: true state: type: string maxLength: 120 nullable: true postalCode: type: string maxLength: 40 nullable: true country: type: string description: ISO 3166-1 alpha-2. pattern: ^[A-Z]{2}$ nullable: true Metadata: type: object additionalProperties: type: string nullable: true description: | Key-value pairs. ≤50 keys, keys ≤40 chars, values are strings ≤500 chars (or `null` to clear). Nested structures must be JSON-stringified into a single string value. SuccessEnvelope: type: object required: - success - data properties: success: type: boolean example: true message: type: string data: description: Endpoint-specific payload. Customer: type: object properties: id: type: string example: cus_abc123 organizationId: type: string email: type: string format: email firstName: type: string nullable: true lastName: type: string nullable: true billingLine1: type: string nullable: true billingLine2: type: string nullable: true billingCity: type: string nullable: true billingState: type: string nullable: true billingPostalCode: type: string nullable: true billingCountry: type: string nullable: true businessName: type: string nullable: true description: Set when the buyer purchased as a business. taxId: type: string nullable: true description: Buyer VAT / fiscal number. externalRef: type: string nullable: true description: >- Merchant business reference set at create/update. Filter with `?externalRef=`. taxRateBps: type: integer nullable: true description: >- VAT rate (bps) for the billing country under the merchant's MoR mode; null for non-MoR merchants. customerAccountEVM: type: string nullable: true customerAccountSOL: type: string nullable: true customerAccountBTC: type: string nullable: true createdAt: type: string format: date-time updatedAt: type: string format: date-time Error: type: object required: - success - error properties: success: type: boolean example: false error: type: string description: Machine-readable error code. example: NOT_FOUND message: type: string example: Resource not found data: description: Optional error detail. ValidationErrorEnvelope: allOf: - $ref: '#/components/schemas/Error' - type: object properties: data: type: object properties: fieldErrors: type: array items: type: object properties: field: type: string message: type: string responses: Unauthorized: description: Invalid or missing API key content: application/json: schema: $ref: '#/components/schemas/Error' example: success: false error: UNAUTHORIZED message: Invalid or missing API key ValidationError: description: Request failed schema validation content: application/json: schema: $ref: '#/components/schemas/ValidationErrorEnvelope' example: success: false error: VALIDATION_ERROR message: Validation failed data: fieldErrors: - field: method message: method is a required field securitySchemes: ApiKeyAuth: type: apiKey in: header name: X-Suby-Api-Key description: Secret API key. `sk_live_…` (production) or `sk_sandbox_…` (sandbox). ````