# Display the APIs Explorer and execute a method

On most documentation pages, a condensed APIs Explorer is visible on the
right-hand side of the screen. If the APIs Explorer isn't visible, click
**Try it!** to display the condensed version of the APIs Explorer.

If **Try it!** doesn't appear on the right-hand side of a reference
documentation page, the method isn't supported by the APIs Explorer. For
example, the APIs Explorer isn't compatible with APIs that require service
accounts, so it doesn't appear on documentation pages for those APIs.

## Display the expanded version of the APIs Explorer

The expanded version of the APIs Explorer contains cURL, HTTP, and possibly
other code samples. To display the expanded version of the APIs Explorer,
click Full screen .

> [!NOTE]
> **Note:** To run the code samples, you must generate and use your own authorization credentials. For an explanation of how to create a project and generate credentials, refer to your specific Google API's documentation.

## Execute a method

The APIs Explorer lets you enter required parameters, optional parameters,
and, if applicable, a request body for API methods. For many REST methods,
such as list methods, you only need to fill one or two fields before you can
execute the method. For example, the Books API's
[`books.volumes.list`](https://developers.google.com/books/docs/v1/reference/volumes/list)
method only requires a query parameter (`q`) to list books. To try the
[`books.volumes.list`](https://developers.google.com/books/docs/v1/reference/volumes/list)
method:

1. Navigate to [`books.volumes.list`](https://developers.google.com/books/docs/v1/reference/volumes/list).
2. If the APIs Explorer isn't displayed, click **Try it!**
3. In the **`q`** field, type *Hunger Games* (without any quotes or special characters).
4. Scroll down and click **Execute**.
5. (optional) A Google sign-in screen asks you to select a Google account.
6. (optional) A Google authorization dialog asks you if it's okay to "Manage your books." Click *Allow*. The results appear below the Execute button.

If the APIs Explorer shows a result of 200, then the method was successful.

> [!NOTE]
> **Note:** After you allow the authorization screen to make an authorized request, the APIs Explorer is authorized to make other requests until the credentials expire. Therefore, you don't see the authorization screen for every subsequent method call. For further information on credentials, see [Test with different credential types and scopes](https://developers.google.com/explorer-help/authorization-and-authentication).

## Troubleshoot APIs Explorer issues

### You received a 401 or 403 error

If you're getting a 401 or 403 error when executing a method using the APIs
Explorer, it is likely due to a problem with one of the following:

- You're using the wrong authorization type (API key instead of OAuth 2.0). Try switching the authorization type.
- You're using OAuth 2.0, but with too narrow a scope. Try using a broader scope.

### Authorization dialog doesn't appear

The APIs Explorer uses a popup to grant access to your private data. If your
browser blocks popups, this popup won't appear and you won't be able to grant
access.

If you click **Allow** in the authorization dialog and nothing happens, try
changing your browser's popup settings to enable popups.