# Set up the Base URL
source: https://developer.mastercard.com/mastercard-checkout-solutions/tutorial/use-postman-for-mastercard-checkout-services-apis/step3/index.md

## 3. Set up the Base URL {#3-set-up-the-base-url}

1. Navigate to the forked environment from the **Environments** tab in your workspace.
   ![Postman](https://static.developer.mastercard.com/content/mastercard-checkout-solutions/documentation/images/postman-setup-baseurl.png "Postman")

2. For the `baseUrl` variable, set the `Current value` with the Sandbox URL value from your API specification.
   ![Postman](https://static.developer.mastercard.com/content/mastercard-checkout-solutions/documentation/images/postman-get-baseurl-from-api.png "Postman")