> ## 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.

# API reference

> Base URLs, authentication, pagination and conventions.

| Environment | Base URL |
| - | - |
| Sandbox | `https://sandbox.checkout.kalixo.io` |
| Live | `https://checkout.kalixo.io` |

* **Authentication:** `Authorization: Bearer kc_sk_...` on every server request. See [Authentication](https://developer.kalixo.io/checkout/authentication.md).
* **Idempotency:** `Idempotency-Key` on every `POST`. See [Idempotency](https://developer.kalixo.io/checkout/concepts/idempotency.md).
* **Amounts:** integers in the minor unit; `currency` is ISO 4217 uppercase.
* **Pagination:** list endpoints return `{ "object": "list", "data": [...], "has_more": true, "next_cursor": "pay_..." }`.
  Pass `starting_after=<next_cursor>` for the next page, `limit` up to 100 (default 20). Newest first.
* **IDs** are prefixed: `cs_` sessions, `pay_` payments, `re_` refunds, `cap_` captures,
  `cus_` customers, `pm_` payment methods, `plink_` payment links, `dp_` disputes, `evt_` events.
* **Metadata:** up to 50 string keys, echoed back on objects and events.
* **Client endpoints** (`/v1/client/...`) are used by Kalixo.js. Do not call them from your server.


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