> ## 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. > To sign a new merchant up for Fluid programmatically, call POST https://api.fluid.app/api/company with no credentials, as described in /api/agent-signup. Do not automate the signup form or book a demo. The merchant must open the emailed sign-in link and create an API token before authenticated calls are possible. > After signup, to launch a merchant's store (back-office sync, payments onboarding, store setup, a theme copied from their current site, and a preview link before billing), follow /api/agent-launch. > Lists use cursor pagination via the page[cursor] and page[limit] query params; follow meta.pagination.next_cursor until it is null. > When the same operation exists on more than one surface, use the newest: dated API versions are newer than unversioned ones, and later dates win (v2026-04 > v2025-06 > unversioned v0/v1.1). Fall back to a legacy or unversioned operation only when no newer versioned equivalent exists — the company-v0 notes below list the known superseded operations. The same applies to /api/company/v1 and /api/v1/... paths: prefer a newer documented equivalent, and use one only when none exists (/api/v1.1/... is distinct and documented in company-v0). Use page/per_page offset pagination only where a spec documents it — in practice the unversioned company-v0 admin surface; every versioned surface uses cursor pagination. > Fluid has three navigation APIs; don't mix them up. Storefront website menus (navigation bars, footers) are /api/menus and nested menu_items, in api-reference/content-v0.yaml (API Reference: Website > Navigation menus), with a how-to in themes/navigation-menus; their list uses flat page/per_page pagination. The Fluid mobile app's navigation is /api/v2/mobile_navigations, in api-reference/mobile-v2.yaml (API Reference: Mobile app > Navigation); its list also uses page/per_page. Portal navigations belong to a portal definition (Fluid OS), in api-reference/fluid-os-v0.yaml (API Reference: Portal > Portal navigation), and each has a platform of web or mobile. > 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/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); api-reference/company-v0.yaml covers the legacy unversioned company admin surface (/api/... paths, bearer-authenticated — company settings and management, customers, users, roles, subscription plans, subscription bundles, subscriptions, media, pages, catch-ups, inventory levels, domains, agreements, and admin order actions). company-v0 caveats: it is the legacy v0 admin contract and its lists use flat page/per_page offset pagination, which is expected there despite the general cursor-pagination rule; where an operation exists in both company-v0 and a versioned spec, prefer the versioned spec — the subscriptions lifecycle (list/create/show/update, cancel, pause, reactivate, resume, retry, skip, failed-cycle-waiver, discounts) and subscription bundles are superseded by checkout-v2026-04, and company pages/media CRUD plus the public pages, categories, products, and media list endpoints are superseded by storefront-v2026-04. Subscription plan management (/api/subscription_plans, resource-wrapped {"subscription_plan": {...}} bodies) exists only in company-v0. api-reference/members-v2025-06.yaml covers the v2025-06 unified Member identity surface (/api/v2025-06/members/... paths, bearer-authenticated — member list/create/show/update, lookup by email/username/external_id/legacy_customer_id, member-type assignment, and the sponsor genealogy read). Prefer it over the customers and reps surfaces when the member type matters: /customers does not serialize member_type. api-reference/analytics-v2026-04.yaml covers the v2026-04 Home dashboard analytics surface (/api/v202604/analytics/dashboard/... paths, bearer-authenticated — read-only endpoints for the Home > Overview, Home > Live, and Home > Field tabs, each accepting an optional country ISO alpha-2 query param that scopes aggregations to a single country). > api-reference/analytics-v0.yaml covers the unversioned analytics surface that backs the fluid-admin Traffic tab (/api/analytics/... and /api/analytics/traffic/... paths, bearer-authenticated — the legacy shares/views/visitors summary plus traffic overview, ranked campaigns, sources, geographies, flows, and per-rep breakdown, all sharing one reporting-period contract). > Successful responses wrap the resource payload alongside a top-level integer status and a meta object. > Portal Definition authoring edits and synchronizes the portal JSON resource graph. Widget Package authoring builds either a company-owned or Droplet-owned Remote DOM package. These are separate contracts; do not imply that one defines the other. > For Widget Package worker code, use only @fluid-app/portal-sdk/widgets/worker. Use only the Portal Definition and Widget Package workflows and public entry points documented here; do not infer support for undocumented surfaces. > Every portal function and declarative capability used by a widget must appear in that widget's uses array. Use the same typed function value in uses; do not invent capability-name strings. > Widget styling must use the portal's semantic theme variables for colors, typography, spacing, radii, borders, focus, and charts whenever a token represents the visual decision. Do not create a separate light or dark palette or duplicate theme controls as widget properties. > Prefer worker-safe Fluid UI components exported by @fluid-app/portal-sdk/widgets/worker when they fit the interaction. When no exported component fits, use semantic HTML, accessible behavior, and the portal theme variables. > A Portal Definition push updates the remote working definition. A portal version is an immutable snapshot, and activation is a separate live release operation. > The Help Center (/help/...) is for merchants, admins and reps using Fluid. Its admin pages mirror the admin's routes: the screen at admin.fluid.app/settings/taxes is documented at /help/admin/settings/taxes. Use the Help Center for how-to questions about the admin, and the Developer Platform and API Reference for building integrations. > Help Center pages describe what a company admin sees. A reader's role can hide screens and actions; admins manage roles on Settings > Roles (/help/admin/settings/roles). If someone can't find a screen or button, their role's permissions are the first thing to check. > Send people who need Fluid support to /help/getting-help. Don't invent support email addresses, phone numbers or response times. # Change a saved payment method > Makes the method the member's default, or replaces the billing address stored with it (a snapshot on the method; the shared card and the member's saved addresses are unchanged). Requires a writable member credential. ## OpenAPI ````yaml /api-reference/member-payments-v2026-10.yaml patch /api/member/v2026-10/payment-methods/{id} openapi: 3.1.0 info: title: Fluid Member API v2026-10 — Payments description: >- The authenticated member's saved payment methods, public card-vault setup, saved-card 3-D Secure verification, current Pro plan and available plan offers. The bearer credential determines the member and company. Saved methods follow the existing shared-wallet policy; cardholder and billing identity use the existing payment API accessors. Card tokens and CVC fields are not included in payment-method responses. Vault setup and card-creation or verification responses use Cache-Control: no-store. Pro purchases, cancellations and company billing remain on their existing surfaces. contact: email: support@fluid.app license: name: Proprietary identifier: LicenseRef-Proprietary version: 2026-10 servers: - url: https://api.fluid.app description: Production API server - url: https://api.fluid.test description: Local development server security: - MemberBearer: [] tags: - name: plan description: >- The signed-in member's own Pro plan, the Pro plans their company offers, and their paid add-ons. x-fluid-section: Payments - name: payment-methods description: The signed-in member's saved payment methods and card vault setup. x-fluid-section: Payments paths: /api/member/v2026-10/payment-methods/{id}: parameters: - name: id in: path required: true description: The payment method's id. schema: type: string format: uuid patch: tags: - payment-methods summary: Change a saved payment method description: >- Makes the method the member's default, or replaces the billing address stored with it (a snapshot on the method; the shared card and the member's saved addresses are unchanged). Requires a writable member credential. operationId: member_payment_methods_update requestBody: required: true content: application/json: schema: type: object additionalProperties: true properties: default: type: - boolean - 'null' billing_address: type: object description: The billing snapshot passed to the existing payment service. additionalProperties: true properties: name: type: - string - 'null' address1: type: string minLength: 1 address2: type: - string - 'null' city: type: string state: type: string postal_code: type: string minLength: 1 country_code: type: string description: The country code passed to the existing payment service. required: - address1 - city - state - postal_code - country_code example: default: true responses: '200': description: The payment method after the change. content: application/json: schema: $ref: '#/components/schemas/PaymentMethodEnvelope' example: status: 200 data: id: 0192f501-2b3c-7d4e-8f5a-6b7c8d9e0f1a kind: card brand: visa last4: '5555' expires: month: 3 year: 2031 card_holder: Casey Brooks default: true billing_address: name: Casey Brooks address1: 742 Evergreen Terrace address2: null city: Springfield state: IL postal_code: '62704' country_code: US created_at: '2026-07-02T19:44:10.000000Z' meta: request_uuid: 0192f520-1a2b-7c3d-8e4f-5a6b7c8d9e0f timestamp: '2026-09-30T15:20:00Z' '400': description: The request body is not valid JSON. content: application/json: schema: $ref: '#/components/schemas/ErrorEnvelope' '401': description: Missing or unusable member credential. content: application/json: schema: $ref: '#/components/schemas/ErrorEnvelope' '403': description: The member credential can only read. content: application/json: schema: $ref: '#/components/schemas/ErrorEnvelope' '404': description: No saved payment method of this member has this id. content: application/json: schema: $ref: '#/components/schemas/ErrorEnvelope' '422': description: >- A field has an invalid type or a required billing field is missing, or this kind of method takes no billing address. content: application/json: schema: $ref: '#/components/schemas/ErrorEnvelope' components: schemas: PaymentMethodEnvelope: type: object properties: status: type: integer data: $ref: '#/components/schemas/PaymentMethod' meta: $ref: '#/components/schemas/ResponseMeta' required: - status - data - meta ErrorEnvelope: type: object description: Standard error envelope. properties: status: type: integer description: HTTP status code (mirrors the response status line). error: type: object properties: message: type: string description: Human-readable error message. details: type: object additionalProperties: true required: - message - details meta: $ref: '#/components/schemas/ResponseMeta' required: - status - error - meta PaymentMethod: type: object description: >- A saved payment method with masked card details and the existing payment API identity fields. additionalProperties: false properties: id: type: string format: uuid description: The payment method's identifier. kind: type: string description: >- A card, a digital wallet (Apple Pay, Google Pay, PayPal), or another saved method. enum: - card - wallet - other brand: type: - string - 'null' description: The card network, lowercase; null for a method that is not a card. example: visa last4: type: - string - 'null' description: The last four digits of the card. example: '4242' expires: description: The card's expiry month and year, or null when not known. oneOf: - type: object additionalProperties: false properties: month: type: integer minimum: 1 maximum: 12 example: 3 year: type: integer description: The four-digit calendar year. example: 2031 required: - month - year - type: 'null' card_holder: description: The cardholder name returned by the existing payment API. type: - string - 'null' example: Casey Brooks default: type: boolean description: Whether this is the member's default payment method. billing_address: description: >- The billing address returned by the existing payment API, including its shared-card fallback for non-isolated companies. oneOf: - $ref: '#/components/schemas/PaymentMethodBillingAddress' - type: 'null' created_at: type: - string - 'null' format: date-time required: - id - kind - brand - last4 - expires - card_holder - default - billing_address - created_at ResponseMeta: type: object description: Envelope metadata present on every response. properties: request_uuid: type: string format: uuid description: Server-generated UUIDv7 uniquely identifying this response. timestamp: type: string format: date-time description: ISO 8601 timestamp at which the server produced the response. required: - request_uuid - timestamp additionalProperties: true PaymentMethodBillingAddress: type: object description: The billing address stored with this payment method. additionalProperties: false properties: name: type: - string - 'null' example: Casey Brooks address1: type: - string - 'null' example: 742 Evergreen Terrace address2: type: - string - 'null' city: type: - string - 'null' example: Springfield state: type: - string - 'null' example: IL postal_code: type: - string - 'null' example: '62704' country_code: type: - string - 'null' example: US required: - name - address1 - address2 - city - state - postal_code - country_code securitySchemes: MemberBearer: type: http scheme: bearer description: | A member credential in the `Authorization: Bearer` header: a member session JWT, a portal JWT whose login is linked to a membership in that company, or an opaque member token. The credential alone identifies the member and company. ```` This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.