> For the complete documentation index, see [llms.txt](https://docs.coupler.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.coupler.io/api/authentication.md).

# Authentication

Send the credential in the `Authorization` header:

```
Authorization: Bearer <token>
```

A value with no scheme is accepted and treated as a bearer token. Any other scheme is left unchanged and will not authenticate.

The token is a personal API token from the [API access section of the user profile](https://app.coupler.io/app/profile). The personal token does not expire. Regenerating it on that page replaces the previous token.

Every request must use HTTPS.

**HTTP methods**

| Method   | Description                             |
| -------- | --------------------------------------- |
| `GET`    | Read a resource or a list of resources. |
| `POST`   | Create a resource.                      |
| `PATCH`  | Update part of a resource.              |
| `PUT`    | Replace a resource.                     |
| `DELETE` | Delete a resource.                      |

**Response codes**

| Code  | Status                | Description                                                                                |
| ----- | --------------------- | ------------------------------------------------------------------------------------------ |
| `200` | OK                    | The request succeeded.                                                                     |
| `201` | Created               | A resource was created.                                                                    |
| `400` | Bad Request           | The request body or query failed validation.                                               |
| `401` | Unauthorized          | The API token is missing or invalid.                                                       |
| `403` | Forbidden             | The user cannot access the workspace, or the billing plan does not include the public API. |
| `404` | Not Found             | The resource was not found.                                                                |
| `422` | Unprocessable Entity  | The request was understood but could not be applied.                                       |
| `429` | Too Many Requests     | The organization exceeded its request allowance. `Retry-After` is `60`.                    |
| `500` | Internal Server Error | An unexpected error occurred.                                                              |
| `502` | Bad Gateway           | An upstream step failed, such as loading field options or storing a query preview.         |

Failed requests return JSON:

```json
{ "error": { "message": "TransformationSet not found" } }
```


---

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```

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