# Using the API test app

The browser-based API test app enables you to make calls to the Payment API of [an integrated Salesforce org](/api/getting-started-with-the-payment-api-v2#step-0-create-a-test-app-integration-optional) directly from the API specification.

With the test app, you can:

- edit any field in sample requests, unrestricted by schemas
- save requests and view request history
- use realistic responses for integration development


## Launch the test app

Launch the test app by clicking the **Try it** button, for instance, on an endpoint action in the API specification.

Try it button launches test app
The app interface opens as an overlay to the API reference specification. The left pane is for testing, while the right pane displays your API call history. To close the test app, click the **X** icon at the top-left corner of the app overlay.

API test app interface
## Send a sample request

To send a sample request, enter the required parameters in the Body tab and click **Send**. The Payment API response is displayed below your request payload.

## Work with environments

Environments combine server URLs with their associated inputs to enable making API calls with a defined set of parameters. You can set up the app to use either a sandbox or production Salesforce org.

Once [these orgs are configured](/api/getting-started-with-the-payment-api-v2#step-0-create-a-test-app-integration-optional), you can switch between environments using the drop-down list in the top-right corner of the app overlay.

Requests are only sent to the active environment. To change which one is active:

1. In the top-right corner, click the **Environments** icon.
2. In the environments list, hover over the the chosen environment's **More options** icon and click **Set as active**.


If you wish to delete an environment, hover over the the chosen environment's **More options** icon and click **Remove environment**.

## History panel

The test app keeps a history of your requests so you can easily check past API calls. The saved requests are grouped by date and display the status code of the response.

You can search your request history as well as delete individual requests or delete the entire history.