> ## Documentation Index
> Fetch the complete documentation index at: https://www.billingserv.com/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# BillingServ Developer Hub

> Build BillingServ integrations with the API, webhooks, OpenAPI reference, and reliable request handling.

Build applications and services that connect to BillingServ.

## Start here

1. Create or copy an API key from [API Settings](/docs/account/api).
2. Follow the [API overview](/docs/api-reference/introduction) to authenticate and make your first request.
3. Explore the complete [API reference](/docs/api-reference), generated from the BillingServ OpenAPI definition.
4. Add event-driven updates with [webhooks](/docs/api-reference/webhooks/overview).

## A first request

Use your API key as a bearer token and start with a read-only customer list request:

```bash theme={null}
curl "https://your-billingserv-domain.com/api/v2/customer/lists" \
  -H "Authorization: Bearer <live_api_key>" \
  -H "Accept: application/json"
```

The API returns an `X-Request-ID` with each response. Keep it with your integration logs so failed requests can be traced quickly.

## Build safely

* Use JSON request bodies and inspect the HTTP status as well as the `success` value.
* Use `Idempotency-Key` for supported customer, invoice, and order create/update operations so retries do not repeat a successful write.
* Read `X-RateLimit-Limit` and `X-RateLimit-Remaining`; limits are configurable by deployment.
* Treat `code` as the machine-readable error category and keep `request_id` with the error.

See the [API overview](/docs/api-reference/introduction) for the supported idempotent operations and response format.

## Receive BillingServ events

Webhooks are the recommended way to react to payments, invoice changes, customer updates, orders, subscriptions, credit notes, and support activity.

* Review the [webhook event reference](/docs/api-reference/webhooks/events).
* Configure the [Webhook Signing Secret](/docs/account/api) and verify `BillingServ-Signature` using the exact raw request body.
* Follow the [endpoint guide](/docs/api-reference/webhooks/build-an-endpoint) for retries, deduplication, and a standalone PHP receiver.

## Keep integrations maintainable

The [OpenAPI document](/docs/api-reference/openapi.json) is the machine-readable contract behind the API reference. Use the documented response headers, error codes, and webhook envelope version when building client libraries or internal integrations.