> ## Documentation Index > Fetch the complete documentation index at: https://developer.kalixo.io/llms.txt > Use this file to discover all available pages before exploring further. # Expire a checkout session > Fails with `payment_in_progress` if an attempt is still being processed. ## OpenAPI ````yaml /checkout/openapi.yaml post /v1/checkout-sessions/{id}/expire openapi: 3.1.0 info: title: Kalixo Checkout API version: '2026-10-01' summary: Payment orchestration API for Kalixo partners. description: > Kalixo Checkout lets partners collect payments from their shoppers through one provider-neutral API. Kalixo is merchant of record and handles payment processing, so partners never integrate a payment provider directly. - Amounts are integers in the currency's minor unit (EUR 49.99 = `4999`). - Server endpoints use a secret key (`kc_sk_test_...` or `kc_sk_live_...`). - Client endpoints are called by `Kalixo.js` with a publishable key and the checkout session's `client_secret`. - Every `POST` with a secret key requires an `Idempotency-Key` header. contact: name: Kalixo Checkout integrations email: integrations@kalixo.io license: name: Proprietary url: https://kalixo.io/legal servers: - url: https://checkout.kalixo.io description: Live - url: https://sandbox.checkout.kalixo.io description: Sandbox (test keys only, connected to the provider test environment) security: - secretKey: [] tags: - name: Checkout sessions description: >- Create a session with the amount to charge, then show it with Kalixo.js or the hosted checkout. - name: Payments description: Read payments and capture or cancel authorized payments. - name: Refunds description: Full and partial refunds of captured payments. - name: Payment links description: Kalixo-hosted payment links that survive provider switches. - name: Customers description: Customers and their stored payment methods for one-click checkout. - name: Disputes description: Chargebacks and information requests, plus evidence upload. - name: Events description: The event log behind webhooks. - name: Webhook endpoints description: Where Kalixo delivers signed events. - name: Reports description: CSV exports of transactions for reconciliation and partner invoicing. - name: Client description: Called by Kalixo.js and the hosted checkout. Not for partner servers. paths: /v1/checkout-sessions/{id}/expire: parameters: - $ref: '#/components/parameters/PathId' post: tags: - Checkout sessions summary: Expire a checkout session description: Fails with `payment_in_progress` if an attempt is still being processed. operationId: expireCheckoutSession parameters: - $ref: '#/components/parameters/IdempotencyKey' responses: '200': description: The expired checkout session. content: application/json: schema: $ref: '#/components/schemas/CheckoutSession' default: $ref: '#/components/responses/Error' components: parameters: PathId: name: id in: path required: true schema: type: string IdempotencyKey: name: Idempotency-Key in: header required: true description: Unique key per logical request, reused on retries. 1 to 255 characters. schema: type: string minLength: 1 maxLength: 255 schemas: CheckoutSession: type: object required: - id - object - status - payment - amount - currency - country - reference - capture_method - return_url - url - expires_at - created_at - livemode - metadata properties: id: type: string examples: - cs_01JABCDEF object: type: string const: checkout_session status: $ref: '#/components/schemas/CheckoutSessionStatus' payment: type: string description: ID of the payment created with this session. amount: $ref: '#/components/schemas/Amount' currency: $ref: '#/components/schemas/Currency' country: $ref: '#/components/schemas/Country' reference: type: string description: The partner's order reference. description: type: - string - 'null' capture_method: $ref: '#/components/schemas/CaptureMethod' customer: type: - string - 'null' customer_email: type: - string - 'null' line_items: type: array items: $ref: '#/components/schemas/LineItem' store_payment_method: type: boolean locale: type: string examples: - en-GB return_url: type: string format: uri url: type: string format: uri description: Hosted checkout URL. Contains the client secret in the URL fragment. client_secret: type: string description: Pass to Kalixo.js. Do not log or store it in analytics. amount_locked: type: boolean description: True once the first payment attempt has started. payment_link: type: - string - 'null' expires_at: type: string format: date-time created_at: type: string format: date-time livemode: type: boolean metadata: $ref: '#/components/schemas/Metadata' CheckoutSessionStatus: type: string enum: - open - complete - expired Amount: type: integer format: int64 minimum: 0 description: Amount in the currency's minor unit. Currency: type: string pattern: ^[A-Z]{3}$ description: ISO 4217 currency code, uppercase. examples: - EUR Country: type: string pattern: ^[A-Z]{2}$ description: ISO 3166-1 alpha-2 country code of the shopper. examples: - NL CaptureMethod: type: string enum: - automatic - manual LineItem: type: object required: - name - quantity - unit_amount properties: name: type: string maxLength: 200 quantity: type: integer minimum: 1 unit_amount: $ref: '#/components/schemas/Amount' tax_amount: $ref: '#/components/schemas/Amount' tax_percentage: type: integer description: Tax percentage in basis points (21% = 2100). sku: type: string maxLength: 100 product_url: type: string format: uri image_url: type: string format: uri Metadata: type: object description: >- Up to 50 keys. Keys up to 40 characters, values up to 500 characters. Echoed back unchanged. additionalProperties: type: string maxLength: 500 maxProperties: 50 ErrorResponse: type: object required: - error properties: error: type: object required: - type - code - message - request_id properties: type: type: string enum: - invalid_request_error - authentication_error - permission_error - not_found_error - idempotency_error - payment_error - rate_limit_error - api_error code: type: string examples: - amount_locked decline_code: type: - string - 'null' message: type: string param: type: - string - 'null' request_id: type: string responses: Error: description: Error. content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' securitySchemes: secretKey: type: http scheme: bearer description: Secret key, `kc_sk_test_...` or `kc_sk_live_...`. Server-side only. ```` This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.