# List customers

`GET https://app.booksbyinstant.com/api/integrator/v1/customers`

The integrator's customers, newest first, a page at a time. Pages hold steady while customers are added. There is no last-use time per customer.

operationId `listCustomers`; tag Customers.

## Example request

cURL:

```bash
curl -X GET 'https://app.booksbyinstant.com/api/integrator/v1/customers' \
  -H "Authorization: Bearer $INTEGRATOR_CREDENTIAL"
```

JavaScript:

```javascript
// Node 18 or later, in an ES module (.mjs), which allows the top-level await.
const res = await fetch("https://app.booksbyinstant.com/api/integrator/v1/customers", {
  method: "GET",
  headers: {
    Authorization: `Bearer ${process.env.INTEGRATOR_CREDENTIAL}`,
  },
});
const data = await res.json();
```

Python:

```python
import os
import requests

res = requests.get(
    "https://app.booksbyinstant.com/api/integrator/v1/customers",
    headers={
        "Authorization": f"Bearer {os.environ['INTEGRATOR_CREDENTIAL']}",
    },
)
data = res.json()
```

## Authorization

- Bearer token `live_<100 hex>`: `Authorization: Bearer <secret>`. A 401 answers `WWW-Authenticate: Bearer realm="instant-integrator-api"`.

## Query parameters

- `limit` (integer; from `1` to `200`; default `50`): How many to answer: a whole number from 1 to 200, without a leading zero.
- `cursor` (string · uuid): The nextCursor of the previous page.

## Responses

### 200

A page of customers.

`application/json`: object

- `items` (array of object; required)
  - `id` (string · uuid; required): The customer's id.
  - `reference` (string; required): The integrator's own reference for the customer.
  - `status` (string; required; one of `active`, `paused`): paused while the integrator has paused the customer.
  - `country` (string or null; required): The customer's ISO 3166-1 alpha-2 country code, in capitals, or null when none is recorded.
  - `createdAt` (string · date-time; required): When the customer was created. ISO 8601 in UTC with milliseconds, such as 2026-11-06T10:00:00.000Z.
  - `pausedAt` (string · date-time or null; required): When the customer was paused, or null while it is active. ISO 8601 in UTC with milliseconds, such as 2026-11-06T10:00:00.000Z.
- `nextCursor` (string · uuid or null; required): The cursor of the next page, or null on the last page.

Example, built from the schema:

```json
{
  "items": [
    {
      "id": "01900000-0000-7000-8000-000000000000",
      "reference": "string",
      "status": "active",
      "country": "string",
      "createdAt": "2026-01-15T09:30:00.000Z",
      "pausedAt": "2026-01-15T09:30:00.000Z"
    }
  ],
  "nextCursor": "01900000-0000-7000-8000-000000000000"
}
```

### 400

A query parameter is unknown or invalid.

`application/json`: object; `Error`

Every answer that is not a success.

- `error` (string; required): Instant's sentence for people. A 4xx keeps the refusal's own sentence; a 5xx always says "Instant is temporarily unavailable. Please try again shortly."
- `code` (string; required): Stable, and what a caller branches on: VALIDATION_ERROR (400), UNAUTHENTICATED (401), FORBIDDEN (403), NOT_FOUND (404), CONFLICT (409), LIMIT_EXCEEDED (413), UNSUPPORTED_MEDIA_TYPE (415), UNREADABLE_FILE (422), RATE_LIMITED (429) and UNAVAILABLE (5xx). More codes may be added; treat one you do not know by its status.
- `retryAfter` (integer; at least `1`): Seconds to wait before retrying, also sent as the `Retry-After` header. Present only when there is a wait, as on a 429.
- `existingId` (string · uuid): On a 409 that names the object already there, such as a customer with that reference: its id.

Example, built from the schema:

```json
{
  "error": "string",
  "code": "VALIDATION_ERROR",
  "retryAfter": 1,
  "existingId": "01900000-0000-7000-8000-000000000000"
}
```

### 401

The credential is missing, malformed, unknown, revoked or rotated, or its integrator is disabled. All of these answer the same way.

Headers:

- `WWW-Authenticate` (string): Bearer realm="instant-integrator-api"

`application/json`: the `Error` object, as in 400.

### 5XX

Instant is temporarily unavailable. Retry later, with backoff.

`application/json`: the `Error` object, as in 400.

---

Page: https://booksbyinstant.com/docs/list-customers/ · Overview: https://booksbyinstant.com/docs/index.md