> ## 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. # Bootstrap a checkout (Kalixo.js) > Returns what Kalixo.js needs to render the checkout, including the renderer chosen by Kalixo's routing. Pins the session to a provider account on first call. ## OpenAPI ````yaml /checkout/openapi.yaml get /v1/client/checkout-sessions/{id} 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/client/checkout-sessions/{id}: parameters: - $ref: '#/components/parameters/PathId' - $ref: '#/components/parameters/ClientSecret' get: tags: - Client summary: Bootstrap a checkout (Kalixo.js) description: | Returns what Kalixo.js needs to render the checkout, including the renderer chosen by Kalixo's routing. Pins the session to a provider account on first call. operationId: clientBootstrapCheckoutSession responses: '200': description: Client view of the checkout session. content: application/json: schema: $ref: '#/components/schemas/ClientCheckoutSession' default: $ref: '#/components/responses/Error' security: - publishableKey: [] - {} components: parameters: PathId: name: id in: path required: true schema: type: string ClientSecret: name: Kalixo-Client-Secret in: header required: true description: The checkout session's `client_secret`. schema: type: string schemas: ClientCheckoutSession: type: object required: - id - status - amount - currency - country - locale - renderer - payment_status properties: id: type: string status: $ref: '#/components/schemas/CheckoutSessionStatus' payment_status: $ref: '#/components/schemas/PaymentStatus' amount: $ref: '#/components/schemas/Amount' currency: $ref: '#/components/schemas/Currency' country: $ref: '#/components/schemas/Country' locale: type: string description: type: - string - 'null' partner_name: type: string store_payment_method: type: boolean return_url: type: string format: uri terms_url: type: string format: uri theme: type: object additionalProperties: true renderer: type: object required: - type - config properties: type: type: string description: >- Identifies the payment form Kalixo.js loads. Opaque; do not rely on specific values. version: type: string config: type: object additionalProperties: true description: Opaque, renderer-specific configuration. CheckoutSessionStatus: type: string enum: - open - complete - expired PaymentStatus: type: string enum: - requires_payment_method - processing - requires_action - authorized - partially_captured - captured - partially_refunded - refunded - canceled - expired - disputed - charged_back Amount: type: integer format: int64 minimum: 0 description: Amount in the currency's minor unit. Currency: type: string pattern: ^[A-Z]{3}$ 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 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. publishableKey: type: http scheme: bearer description: >- Publishable key, `kc_pk_test_...` or `kc_pk_live_...`. Safe for browsers. ```` This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.