> For the complete documentation index, see [llms.txt](https://docs.partssource.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.partssource.com/api/getting-started/request-headers.md).

# Request headers

This page documents the HTTP headers used when making requests to PartsSource APIs.

## Authorization

All API requests require an `Authorization` header with a Bearer token:

```
Authorization: Bearer {your-access-token}
```

See [Authentication](/api/authentication/overview.md) for details on obtaining an access token.

## Idempotency-Key

The `Idempotency-Key` header is **required** for order creation (`POST /orders`) and prevents duplicate orders when retrying failed requests.

### Purpose

Network failures, timeouts, or client errors can cause uncertainty about whether a request succeeded. Without idempotency, retrying a `POST /orders` request could create duplicate orders. The `Idempotency-Key` header ensures that retrying the same request returns the original response instead of creating a new order.

### Format

The header value must be a valid UUID (version 4 recommended):

```
Idempotency-Key: 550e8400-e29b-41d4-a716-446655440000
```

### Example Request

```bash
curl --location \
--request POST 'https://api.partssource.com/customer/orders' \
--header 'Content-Type: application/json' \
--header 'Authorization: Bearer {your-access-token}' \
--header 'Idempotency-Key: 550e8400-e29b-41d4-a716-446655440000' \
--data '{
  "facilityId": "FAC-001",
  "lineItems": [
    {
      "partNumber": "PART-12345",
      "quantity": 1
    }
  ]
}'
```

### Behavior

| Scenario                         | Result                                             |
| -------------------------------- | -------------------------------------------------- |
| First request with a new key     | Order is created, response returned                |
| Retry with the same key          | Original response is returned (no duplicate order) |
| New request with a different key | New order is created                               |

### Best Practices

* Generate a new UUID for each unique order intent
* Store the key before sending the request so you can retry with the same key if needed
* Do not reuse keys across different orders
* Keys are typically valid for 24 hours

## Content-Type

For requests with a body (`POST`, `PUT`, `PATCH`), include:

```
Content-Type: application/json
```


---

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