# HTTP and REST

The REST URL structure follows typical resource-oriented conventions.

To get a list of sheets, use the following:

`GET https://api.smartsheet.com/2.0/sheets`

This returns a list of Sheet objects, where each sheet has an **id** attribute.

To get details on the sheet with **id 123456**, use the following:

`GET https://api.smartsheet.com/2.0/sheets/123456`

This ID pattern is repeated throughout the API. Columns, rows, cells, comments, attachments, or any other data element have a unique ID.

If you don't want to make raw HTTP calls, Smartsheet also has several Software Development Kits (SDKs) that provide a higher level interface for popular programming languages. For more information, see [SDKs and Samples](/api/smartsheet/guides/additional-resources#sdks-and-samples).

## HTTP Verbs

Call the API using the following standard HTTP methods:

* GET (to retrieve an object or list multiple objects in a specific category)
* POST (to create)
* PUT (to modify)
* DELETE


## HTTP Headers

Unless otherwise specified, all API endpoints expect request body data to be in JSON, and the response body data is returned as JSON.

The following HTTP request headers may be required, depending on the operation and endpoint being invoked:

| Header | Definition | Example |
|  --- | --- | --- |
| **Authorization** | Required for all endpoints, except for `POST /token`. The access token. | `Bearer JKlMNOpQ12RStUVwxYZAbcde3F5g6hijklM789` |
| **Content-Type** | Required for POST and PUT requests. Defines the structure for the response. | `application/json` |
| **smartsheet-integration-source** | Specifies the following information about the service request:  Integration type  Smartsheet organization name Client integrator name   Format: `INTEGRATION-TYPE,SMAR-ORGANIZATION-NAME,INTEGRATOR-NAME`   Important: All three elements, and the commas that separate them, are required.   You can set `INTEGRATION-TYPE` to `AI`, `SCRIPT`, `APPLICATION`, or `PERSONAL_ACCOUNT`. | `AI,Sample-Organization,AI-Integrator-v2` |
| **Assume-User** | Optional. As a System Admin, you can impersonate or make API calls on behalf of any user (even another System Admin) in your plan by setting `Assume-User` to that user's email address.   **Note:** In commands, such as cURL, you must URI-encode the email address. | `jane.doe%40smartsheet.com` |


## HTTP Status Codes

Smartsheet uses a combination of HTTP status codes and custom error codes with a descriptive message in JSON-formatted [Error objects](/api/smartsheet/openapi/schemas/error) to give you a more complete picture of what has happened with your request.

| HTTPstatus code | Meaning | To Retry or Not to Retry? |
|  --- | --- | --- |
| 2xx | Request was successful.Example: 200 Success | -- |
| 4xx | A problem with request prevented it from executing successfully. | Never automatically retry the request.If the error code indicates a problem that can be fixed, fix the problem and retry the request. |
| 5xx | The request was properly formatted, but the operation failed on Smartsheet's end. | In some scenarios, requests should be automatically retried using exponential backoff. |


For example, doing a `GET` on a non-existent sheet at `https://api.smartsheet.com/2.0/sheets/123456` results in an HTTP status code of **404**, indicating the resource was not found.


```json
{
"errorCode": 1006,
"message": "Not Found"
}
```

br
Some errors may contain a **detail** attribute set to an object with additional error details that may be useful in programmatically handling the error.  If so, it is noted in the specific API operation for which the error may occur.

NOTE: Smartsheet has custom error codes to help you troubleshoot issues. See [Error Codes](/api/smartsheet/error-codes).