> ## Documentation Index > Fetch the complete documentation index at: https://docs.withflex.com/llms.txt > Use this file to discover all available pages before exploring further. # Create Setup Intent > Creates a SetupIntent to collect a customer's payment method details for future off-session use. A new SetupIntent is created on each call and starts in the `requires_payment_method` status; it is not an upsert. The response includes a `client_secret` that you use to confirm the SetupIntent and attach a payment method from your frontend. ## OpenAPI ````yaml /openapi.json post /v1/setup_intents openapi: 3.1.0 info: title: Flex API description: >- The Flex API powers HSA/FSA payment processing for healthcare commerce: checkout sessions, payment intents, subscriptions, customers, refunds, disputes, and eligibility. Authenticate with your partner API key as a Bearer token. All endpoints are scoped to your partner account, and test mode is fully supported via test API keys. version: 0.1.0 servers: - url: https://api.withflex.com security: - BearerAuth: [] tags: - name: Balance Transactions - name: Captures - name: Checkout Sessions - name: Coupons - name: Customers - name: Disputes - name: Events - name: Exports - name: Files - name: Invoices - name: Letters - name: Orders - name: Payment Intents - name: Payment Links - name: Payouts - name: Prices - name: Products - name: Promo Codes - name: Receipts - name: Refunds - name: Setup Intents - name: Shipping Rates - name: Subscriptions paths: /v1/setup_intents: post: tags: - Setup Intents summary: Create Setup Intent description: >- Creates a SetupIntent to collect a customer's payment method details for future off-session use. A new SetupIntent is created on each call and starts in the `requires_payment_method` status; it is not an upsert. The response includes a `client_secret` that you use to confirm the SetupIntent and attach a payment method from your frontend. operationId: v1.setup_intents.create requestBody: description: An envelope wrapping a single setup intent object. content: application/json: schema: $ref: '#/components/schemas/SetupIntentBody_for_CreateSetupIntent' example: setup_intent: partner_id: facct_01J9XR8M3K7VZ8N2YB4WJ6T0RA checkout_session: fcs_01J9XR8M3K7VZ8N2YB4WJ6T0RA required: true responses: '200': description: Success content: application/json: schema: $ref: '#/components/schemas/SetupIntentBody_for_SetupIntent' example: setup_intent: setup_intent_id: fseti_01J9XR8M3K7VZ8N2YB4WJ6T0RA description: Premium SPF 50 mineral sunscreen payment_method: fpm_01J9XR8M3K7VZ8N2YB4WJ6T0RA partner_id: facct_01J9XR8M3K7VZ8N2YB4WJ6T0RA metadata: order_id: '8842' channel: shopify created_at: '2026-06-15T14:30:00Z' test_mode: false status: requires_payment_method usage: off_session subscription_id: fsub_01J9XR8M3K7VZ8N2YB4WJ6T0RA '401': description: Unauthorized content: application/json: schema: $ref: '#/components/schemas/HttpErrorOut' example: code: string detail: string '403': description: Forbidden content: application/json: schema: $ref: '#/components/schemas/HttpErrorOut' example: code: string detail: string '404': description: Not Found content: application/json: schema: $ref: '#/components/schemas/HttpErrorOut' example: code: string detail: string '409': description: Conflict content: application/json: schema: $ref: '#/components/schemas/HttpErrorOut' example: code: string detail: string '422': description: Validation Error content: application/json: schema: $ref: '#/components/schemas/HTTPValidationError' example: detail: - loc: - string msg: string type: string '429': description: Too Many Requests content: application/json: schema: $ref: '#/components/schemas/HttpErrorOut' example: code: string detail: string components: schemas: SetupIntentBody_for_CreateSetupIntent: description: An envelope wrapping a single setup intent object. type: object required: - setup_intent properties: setup_intent: $ref: '#/components/schemas/CreateSetupIntent' description: The SetupIntent. example: setup_intent: partner_id: facct_01J9XR8M3K7VZ8N2YB4WJ6T0RA checkout_session: fcs_01J9XR8M3K7VZ8N2YB4WJ6T0RA SetupIntentBody_for_SetupIntent: description: An envelope wrapping a single setup intent object. type: object required: - setup_intent properties: setup_intent: $ref: '#/components/schemas/SetupIntent' description: The SetupIntent. example: setup_intent: setup_intent_id: fseti_01J9XR8M3K7VZ8N2YB4WJ6T0RA description: Premium SPF 50 mineral sunscreen payment_method: fpm_01J9XR8M3K7VZ8N2YB4WJ6T0RA partner_id: facct_01J9XR8M3K7VZ8N2YB4WJ6T0RA metadata: order_id: '8842' channel: shopify created_at: '2026-06-15T14:30:00Z' test_mode: false status: requires_payment_method usage: off_session subscription_id: fsub_01J9XR8M3K7VZ8N2YB4WJ6T0RA HttpErrorOut: title: HttpError description: The error response returned when a request cannot be completed. type: object required: - code - detail properties: code: description: A short machine-readable error code identifying the type of error. type: string detail: description: A human-readable explanation of what went wrong. type: string example: code: string detail: string HTTPValidationError: description: The error response returned when request validation fails (HTTP 422). type: object required: - detail properties: detail: description: The list of validation errors, one entry per invalid field. type: array items: $ref: '#/components/schemas/ValidationErrorItem' example: detail: - loc: - string msg: string type: string CreateSetupIntent: description: >- Parameters for creating a SetupIntent to collect a customer's payment method details. type: object required: - checkout_session - partner_id properties: partner_id: description: ID of the account the SetupIntent is created for. type: string example: facct_01J9XR8M3K7VZ8N2YB4WJ6T0RA checkout_session: description: ID of the CheckoutSession the SetupIntent is associated with. type: string example: fcs_01J9XR8M3K7VZ8N2YB4WJ6T0RA example: partner_id: facct_01J9XR8M3K7VZ8N2YB4WJ6T0RA checkout_session: fcs_01J9XR8M3K7VZ8N2YB4WJ6T0RA SetupIntent: description: >- A SetupIntent represents your intent to set up a customer's payment method for future payments, without charging it immediately. Use it to collect and verify payment method details that can later be used off-session (for example, to bill a subscription or invoice). type: object required: - created_at - partner_id - setup_intent_id - status - test_mode - usage properties: setup_intent_id: description: The unique identifier for the object. type: string example: fseti_01J9XR8M3K7VZ8N2YB4WJ6T0RA client_secret: description: >- The client secret used to confirm this SetupIntent from your frontend. Present when the SetupIntent is retrieved or created; `null` when it appears in a list response. Treat it as sensitive: do not log or store it, and expose it only to the customer over TLS. type: - string - 'null' customer: description: >- The Customer this SetupIntent belongs to; returned as the ID by default and expandable to the full object. anyOf: - $ref: '#/components/schemas/Expandable_for_Customer' - type: 'null' description: description: An arbitrary string attached to the setup intent. type: - string - 'null' example: Premium SPF 50 mineral sunscreen payment_method: description: Payment method used with this SetupIntent. type: - string - 'null' example: fpm_01J9XR8M3K7VZ8N2YB4WJ6T0RA partner_id: description: The ID of the account this SetupIntent belongs to. type: string example: facct_01J9XR8M3K7VZ8N2YB4WJ6T0RA metadata: description: >- Set of key-value pairs that you can attach to an object. This can be useful for storing additional information about the object in a structured format. type: - object - 'null' additionalProperties: type: object example: order_id: '8842' channel: shopify created_at: $ref: '#/components/schemas/Timestamptz' description: Time at which the object was created. ISO 8601 format. example: '2026-06-15T14:30:00Z' test_mode: description: Whether or not the setup intent is in test mode. type: boolean example: false status: $ref: '#/components/schemas/Status2' description: The current status of the setup intent. usage: $ref: '#/components/schemas/Usage' description: >- Indicates how the payment method is intended to be used in the future. subscription_id: description: >- The ID of the Subscription this SetupIntent is associated with (for payment method updates). type: - string - 'null' example: fsub_01J9XR8M3K7VZ8N2YB4WJ6T0RA example: setup_intent_id: fseti_01J9XR8M3K7VZ8N2YB4WJ6T0RA customer: fcus_01J9XR8M3K7VZ8N2YB4WJ6T0RA description: Premium SPF 50 mineral sunscreen payment_method: fpm_01J9XR8M3K7VZ8N2YB4WJ6T0RA partner_id: facct_01J9XR8M3K7VZ8N2YB4WJ6T0RA metadata: order_id: '8842' channel: shopify created_at: '2026-06-15T14:30:00Z' test_mode: false status: requires_payment_method usage: off_session subscription_id: fsub_01J9XR8M3K7VZ8N2YB4WJ6T0RA ValidationErrorItem: description: >- Validation errors have their own schema to provide context for invalid requests eg. mismatched types and out of bounds values. There may be any number of these per 422 UNPROCESSABLE ENTITY error. type: object required: - loc - msg - type properties: loc: description: >- The location as a [`Vec`] of [`String`]s -- often in the form `["body", "field_name"]`, `["query", "field_name"]`, etc. They may, however, be arbitarily deep. type: array items: type: string msg: description: The message accompanying the validation error item. type: string type: description: >- The type of error, often "type_error" or "value_error", but sometimes with more context like as "value_error.number.not_ge" type: string example: loc: - string msg: string type: string Expandable_for_Customer: anyOf: - type: string example: fcus_01J9XR8M3K7VZ8N2YB4WJ6T0RA - $ref: '#/components/schemas/Customer' example: fcus_01J9XR8M3K7VZ8N2YB4WJ6T0RA description: An expandable field — either a string ID or an expanded Customer object. Timestamptz: description: >- A timestamp encoded as an RFC 3339 / ISO 8601 string (e.g. `2026-06-15T14:30:00Z`). type: string example: string Status2: description: The status of the setup intent. type: string enum: - requires_payment_method - requires_confirmation - requires_action - processing - succeeded - canceled example: requires_payment_method Usage: description: >- Whether the saved payment method is intended for off-session or on-session future payments. type: string enum: - off_session - on_session example: off_session Customer: description: >- A Customer object represents a customer of your business. Use it to track payments, store reusable payment methods, and reference the customer on checkout sessions, invoices, and subscriptions. type: object required: - created_at - customer_id - email - first_name - last_name - test_mode properties: customer_id: description: The unique identifier for the customer. type: string example: fcus_01HACM7FZ1084XB1GB6053VM0D owner_partner_id: description: >- The partner that owns this customer. When a customer is shared with you by another partner in your organization, this is that sibling partner; otherwise it is your own partner id. type: - string - 'null' example: obj_01J9XR8M3K7VZ8N2YB4WJ6T0RA first_name: description: The customer's first name. type: string example: John last_name: description: The customer's last name. type: string example: Doe email: description: The customer's email address. type: string format: email example: joh.doe@example.com phone: description: The customer's phone number. type: - string - 'null' format: phone example: '+15555555555' employer: description: The customer's employer. type: - string - 'null' example: Flex shipping: description: The customer's shipping address. anyOf: - $ref: '#/components/schemas/ShippingAddress' - type: 'null' metadata: description: Metadata associated with the customer. type: - object - 'null' additionalProperties: type: string example: order_id: '8842' channel: shopify created_at: $ref: '#/components/schemas/Timestamptz' description: The time the customer was created. example: '2026-06-15T14:30:00Z' test_mode: description: Whether the customer was created in test mode. type: boolean example: false example: customer_id: fcus_01HACM7FZ1084XB1GB6053VM0D owner_partner_id: obj_01J9XR8M3K7VZ8N2YB4WJ6T0RA first_name: John last_name: Doe email: joh.doe@example.com phone: '+15555555555' employer: Flex shipping: shipping_address_id: fsh_01J9XR8M3K7VZ8N2YB4WJ6T0RA line1: 123 Main St line2: Suite 100 city: San Francisco state: CA postal_code: '94107' country: US metadata: order_id: '8842' channel: shopify created_at: '2026-06-15T14:30:00Z' test_mode: false ShippingAddress: description: >- A ShippingAddress represents the postal address a physical order is delivered to. It is referenced by checkout sessions and customers. type: object required: - shipping_address_id properties: shipping_address_id: description: Unique identifier for the shipping address. type: string example: fsh_01J9XR8M3K7VZ8N2YB4WJ6T0RA line1: description: The first line of the street address (e.g., street number and name). type: - string - 'null' example: 123 Main St line2: description: >- The second line of the street address (e.g., apartment, suite, or unit). type: - string - 'null' example: Suite 100 city: description: City, district, suburb, town, or village. type: - string - 'null' example: San Francisco state: description: State, county, province, or region. type: - string - 'null' example: CA postal_code: description: ZIP or postal code. type: - string - 'null' example: '94107' country: description: Two-letter country code (ISO 3166-1 alpha-2, e.g., `US`). type: - string - 'null' example: US example: shipping_address_id: fsh_01J9XR8M3K7VZ8N2YB4WJ6T0RA line1: 123 Main St line2: Suite 100 city: San Francisco state: CA postal_code: '94107' country: US securitySchemes: BearerAuth: type: http scheme: bearer bearerFormat: API Key description: Use a Bearer token to access this API. ````