> ## Documentation Index > Fetch the complete documentation index at: https://docs.fluid.app/llms.txt > Use this file to discover all available pages before exploring further. > ## Agent Instructions > For new direct REST integrations, use the v2026-04 surfaces. The @fluid-app FairShare SDK continues to use its own published public-v2025-06 contract. > Authenticate with the header Authorization: Bearer ; public storefront read endpoints require no auth. > Lists use cursor pagination via the page[cursor] and page[limit] query params; follow meta.pagination.next_cursor until it is null. > Never use /api/company/v1 or /api/v1 paths, page/per_page params, or offset pagination — they are legacy. > The OpenAPI specs under api-reference/ are the authoritative contracts; prefer them over prose when in doubt. api-reference/storefront-v2026-04.yaml covers the v2026-04 storefront surface (/api/v202604/... paths); api-reference/auth-v0.yaml covers the unversioned auth surface (/api/... paths — authentication, MFA, social auth, and token exchange); api-reference/checkout-v2026-04.yaml covers the v2026-04 checkout surface (/api/checkout/v2026-04/... paths — carts, cart auth, discounts, items, subscriptions, orders, enrollments, and store config); api-reference/public-v2025-06.yaml covers the Public SDK surface used by the @fluid-app FairShare SDK, including its parallel cart lifecycle, browser integrations, versioned payment callbacks, unversioned public utilities, and the cart price-override operation; api-reference/payment-v2026-04.yaml covers the v2026-04 payment gateway admin surface (/api/payment/v2026-04/... paths, bearer-authenticated — gateway CRUD, gateway purchase/authorize/$0-verify, transaction list/show and capture/void/credit, and merchant payment configuration); api-reference/payments-v2026-04.yaml covers the v2026-04 cart payment surface (/api/payments/v2026-04/carts/{cart_token}/... paths, authenticated by the cart token in the path with no bearer — payment-method selection, VGS card tokenization, 3D Secure verification, and PayPal/Braintree/Klarna/Apple Pay flows); api-reference/commerce-v2026-04.yaml covers the v2026-04 commerce order-editing surface (/api/v202604/orders/{order_id}/edits paths, bearer-authenticated — post-checkout order edits that atomically insert items and add adjustments/discounts, with an optional dry-run preview); api-reference/webhooks-v0.yaml covers the unversioned webhooks surface (/api/... paths — webhook registration, delivery payloads, callback registrations, company events, and webhook/callback schemas). > Successful responses wrap the resource payload alongside a top-level integer status and a meta object. # Create customer payment method > Saves a payment method on the authenticated customer's account. Requires `type`, `country_code`, and a `payment_method` payload; set `default_payment_method: true` to make it the default. Requires a customer bearer token. Returns `422` on validation or tokenization failure and `401` when unauthenticated. ## OpenAPI ````yaml /api-reference/checkout-v2026-04.yaml post /api/checkout/v2026-04/customers/me/payment_methods openapi: 3.1.0 info: title: Fluid Checkout API description: >- **Fluid Checkout API — for building a checkout directly against REST.** Use this surface if you are integrating server-to-server or building your own checkout UI. It covers the full order lifecycle (cart → address → shipping → discount → complete → order) plus the logged-in customer's account: saved addresses, saved payment methods, order history, loyalty points, and subscription management (pause, resume, skip, cancel, retry). **The cart token in the URL scopes cart access** — creating a cart, adding items, applying a discount, and completing a cart need no bearer token. Among the cart operations, a Bearer token is required only for `carts/{cart_token}/sync`, `carts/{cart_token}/volume_rep`, and `carts/{cart_token}/discount/manual`. Off the cart, a token is required for everything under `customers/me` and `subscriptions`, and for the store and directory lookups (`store/config`, `store/languages`, `reps`, `users`) and `subscription_bundles`. `store/countries` accepts a token but does not require one — it returns the same list either way. **If you are using the `@fluid-app` FairShare SDK in a theme or storefront, you are not calling this surface** — the SDK calls the Fluid Public SDK API (`public-v2025-06`). Do not mix the two against one cart: they share the same cart records and services, but their request shapes differ. See [Choosing a cart surface](https://docs.fluid.app/api/choosing-a-cart-surface) for the operation map and boundary. version: v2026-04 contact: email: support@fluid.app license: name: Proprietary identifier: LicenseRef-Proprietary servers: - url: https://api.fluid.app security: [] tags: - name: carts description: >- Create, read, and mutate checkout carts (email, address, country, language, shipping, recalculation, completion). - name: cart-auth description: >- Cart-scoped customer authentication — magic-link challenge, verification, identity, and logout. - name: cart-discount description: >- Apply, list, and remove cart discount codes, including admin manual discounts. - name: cart-items description: Add, update, and remove line items on a cart. - name: cart-points description: Apply and remove loyalty points on a cart. - name: customers description: The authenticated customer's profile and company memberships. - name: customer-addresses description: The authenticated customer's saved shipping/billing addresses. - name: customer-orders description: The authenticated customer's order history. - name: customer-payment-methods description: The authenticated customer's saved payment methods and tokenization. - name: customer-points description: The authenticated customer's loyalty point balances. - name: directory description: Company rep and user directory lookups. - name: enrollments description: >- Public enrollment forms — retrieve a form and submit, update, or upload field answers. - name: orders description: Public order lookup by token. - name: products description: Public product queries for the storefront checkout. - name: store description: >- Store-level checkout configuration — countries, languages, address fields, agreements, drop zones, and Apple Pay domain verification. - name: subscriptions description: >- Manage subscriptions — pause, resume, skip, cancel, reactivate, retry, and failed-cycle waivers. - name: subscription-bundles description: List and create subscription bundles. paths: /api/checkout/v2026-04/customers/me/payment_methods: post: tags: - customer-payment-methods summary: Create customer payment method description: > Saves a payment method on the authenticated customer's account. Requires `type`, `country_code`, and a `payment_method` payload; set `default_payment_method: true` to make it the default. Requires a customer bearer token. Returns `422` on validation or tokenization failure and `401` when unauthenticated. operationId: checkout_v2026_04_create_customer_payment_method requestBody: content: application/json: schema: type: object additionalProperties: false required: - type - country_code - payment_method properties: type: type: string description: Payment method type example: credit_card country_code: type: string description: ISO country code for the checkout country example: US payment_method: type: object additionalProperties: false required: - token properties: token: type: string description: Tokenized payment credential token_provider: type: string description: Token provider identifier cvv_token: type: string description: Tokenized CVV credential exp_month: type: integer example: 12 exp_year: type: integer example: 2028 card_holder: type: string description: Cardholder name payment_account_id: description: Payment account ID override bin: type: - string - 'null' description: >- First six digits of the card number forwarded from VGS Collect for brand/BIN persistence. example: '424242' last_four: type: - string - 'null' description: >- Last four digits of the card number, forwarded from VGS Collect for display persistence. example: '4242' card_network: type: - string - 'null' description: >- Card network (e.g. visa, mastercard) forwarded from VGS Collect for brand persistence. example: visa default_payment_method: type: boolean description: Whether to set this as the default payment method billing_address: type: object additionalProperties: false required: - address1 - city - state - zip - country_code properties: address1: type: - string - 'null' address2: type: - string - 'null' city: type: - string - 'null' state: type: - string - 'null' zip: type: - string - 'null' country_code: type: - string - 'null' example: US name: type: - string - 'null' browser_info: type: object additionalProperties: true description: >- Flat browser device fingerprint for 3DS authentication, as produced by the checkout client's getBrowserInfo() (fluid-pay-core browserInfoSchema). properties: color_depth: type: - integer - 'null' example: 24 screen_height: type: - integer - 'null' example: 1080 screen_width: type: - integer - 'null' example: 1920 time_zone: type: - integer - 'null' description: Timezone offset in minutes (Date#getTimezoneOffset) example: -300 java_enabled: type: - boolean - 'null' java_script_enabled: type: - boolean - 'null' language: type: - string - 'null' example: en-US user_agent: type: - string - 'null' accept_header: type: - string - 'null' example: '*/*' payment_account: type: - string - 'null' description: Payment account UUID override set_customer_payment_method: type: boolean description: >- When true, binds the payment method to the customer rather than the FluidPay account responses: '200': description: Success content: application/json: schema: $ref: >- #/components/schemas/CheckoutCustomerPaymentMethodCreateResponse '401': description: Unauthorized content: application/json: schema: $ref: '#/components/schemas/UnauthorizedResponse' '422': description: Unprocessable Entity content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' security: - bearer_auth: [] components: schemas: CheckoutCustomerPaymentMethodCreateResponse: type: object properties: card: type: object properties: active: type: boolean address_id: type: - integer - 'null' billing_address: type: - object - 'null' properties: name: type: - string - 'null' address1: type: - string - 'null' address2: type: - string - 'null' address3: type: - string - 'null' city: type: - string - 'null' state: type: - string - 'null' postal_code: type: - string - 'null' country_code: type: - string - 'null' subdivision_code: type: - string - 'null' card_network: type: - string - 'null' created_at: type: string format: date-time customer_id: type: - integer - 'null' cvv_token: type: - string - 'null' default: type: boolean email: type: - string - 'null' fingerprint: type: - string - 'null' first_six_digits: type: - string - 'null' fluid: type: boolean fluid_pay_account_id: type: - integer - 'null' full_name: type: - string - 'null' last_four_digits: type: - string - 'null' member_id: type: - string - 'null' format: uuid month: type: - integer - 'null' number: type: - string - 'null' test: type: boolean token: type: string token_provider: type: string updated_at: type: string format: date-time user_id: type: - integer - 'null' uuid_v7: type: string year: type: - integer - 'null' required: - active - card_network - created_at - customer_id - cvv_token - default - email - fingerprint - first_six_digits - fluid - fluid_pay_account_id - full_name - last_four_digits - member_id - month - number - test - token - token_provider - updated_at - user_id - uuid_v7 - year additionalProperties: false customer: type: - object - 'null' properties: default_payment_method_id: type: - integer - 'null' id: type: integer required: - default_payment_method_id - id additionalProperties: false fluid_pay_account: type: - object - 'null' properties: default_payment_method_id: type: - integer - 'null' id: type: integer required: - default_payment_method_id - id additionalProperties: false meta: $ref: '#/components/schemas/Meta' payment_method: $ref: '#/components/schemas/CheckoutPaymentMethod' was_created: type: boolean required: - card - fluid_pay_account - meta - payment_method - was_created additionalProperties: false UnauthorizedResponse: type: object properties: message: type: string required: - message ErrorResponse: type: object additionalProperties: false required: - error_message - errors - meta properties: error_message: type: string errors: $ref: '#/components/schemas/ErrorBag' meta: $ref: '#/components/schemas/CheckoutMeta' Meta: type: object properties: request_id: type: - string - 'null' timestamp: type: string format: date-time CheckoutPaymentMethod: type: object properties: au_status: type: - string - 'null' billing_address: type: - object - 'null' properties: address1: type: - string - 'null' address2: type: - string - 'null' city: type: - string - 'null' country_code: type: - string - 'null' name: type: - string - 'null' postal_code: type: - string - 'null' state: type: - string - 'null' zip: type: - string - 'null' required: - address1 - address2 - city - country_code - name - postal_code - state - zip additionalProperties: false created_at: type: string format: date-time default: type: boolean details: $ref: '#/components/schemas/CheckoutPaymentMethodDetails' id: type: integer payment_title: type: string payment_type: type: string source: type: string updated_at: type: string format: date-time required: - au_status - billing_address - created_at - default - details - id - payment_title - payment_type - source - updated_at additionalProperties: false ErrorBag: description: >- Validation errors keyed by field, a list of errors, a single error message, or null when no structured error details are available. anyOf: - type: string - type: array items: $ref: '#/components/schemas/ErrorValue' - type: object additionalProperties: $ref: '#/components/schemas/ErrorValue' - type: 'null' CheckoutMeta: type: object additionalProperties: false required: - request_id - timestamp properties: request_id: type: - string - 'null' timestamp: type: string format: date-time CheckoutPaymentMethodDetails: type: object properties: card_brand: type: - string - 'null' card_network: type: - string - 'null' exp_month: type: - string - 'null' exp_year: type: - string - 'null' id: type: integer last4_digits: type: - string - 'null' last_four: type: - string - 'null' logo_url: type: - string - 'null' requires_3ds: type: - boolean - 'null' type: type: - string - 'null' vgs_card_id: type: - string - 'null' required: - card_brand - card_network - exp_month - exp_year - id - last4_digits - last_four - logo_url - requires_3ds - type - vgs_card_id additionalProperties: false ErrorValue: description: A validation or API error value. anyOf: - type: string - type: array items: type: string - type: object additionalProperties: $ref: '#/components/schemas/JsonValue' JsonValue: description: >- Any valid JSON value for provider, integration, theme, metadata, or other dynamic payloads whose keys are not fixed by the API contract. anyOf: - type: string - type: number - type: boolean - type: 'null' - type: array items: $ref: '#/components/schemas/JsonValue' - type: object additionalProperties: $ref: '#/components/schemas/JsonValue' securitySchemes: bearer_auth: type: http scheme: bearer description: Bearer token authentication ````