# Sandbox
source: https://developer.mastercard.com/bill-payment-validator/documentation/tutorials-and-guides/sandbox-key/index.md

## Overview {#overview}

To start using the RPPS Bill Paymenet Validator Service, you must set up a project in Mastercard Developers (which creates the necessary project keys) and complete testing in the Sandbox environment before proceeding to the MTF environment. Sandbox testing cannot begin until you've received a key as described below.

**What you'll learn:**

* Create a new RPPS Bill Payment Validator Service project
* Obtain the key required for the Sandbox environment
* Get access to the Sandbox environment   

  The following steps assume you have already completed and returned the Mastercard Bill Pay agreements and enrollment forms.

## Step 1: Create a New Mastercard Developers project {#step-1-create-a-new-mastercard-developers-project}

[Create New Project](https://developer.mastercard.com/dashboard).
Click on the Create New Project button to start the process.
![Project Details](https://static.developer.mastercard.com/content/bill-payment-validator/uploads/project-details.png)
Give your project a name, this name will be used throughout the process unless you decide to use another approach.
Leave the default of "Are you creating a project on behalf of a client?" as "No".  


Select **RPPS Bill Payment Validator Service** .
![Bill Payment Validator Service](https://static.developer.mastercard.com/content/bill-payment-validator/uploads/selectApi.png)
**Click Proceed**

## Step 2: Enter your Project Key {#step-2-enter-your-project-key}

**Enter your Keystore alias and Keystore password**
![Sandbox Credentials](https://static.developer.mastercard.com/content/bill-payment-validator/uploads/credentials.png)
**Click Proceed**

## Step 3: Download key file {#step-3-download-key-file}

**Download your key file to use for validating your credentials**
![Download Key file](https://static.developer.mastercard.com/content/bill-payment-validator/uploads/downloadkeyfile.png)
**Open Project**

## Step 4: Ready to Test in Sandbox {#step-4-ready-to-test-in-sandbox}

You should see the following once you go back to your project:
![Download Key file](https://static.developer.mastercard.com/content/bill-payment-validator/uploads/sandboxsummary.png)
You will copy the Sandbox Client ID and setup your environment with the Key alias and KeyStore password created in Step 2.

**You now have everything you need to start sending RPPS Bill Payment Validator Service requests to the Sandbox!**

In the Sandbox environment, RPPS Bill Payment Validator Service is mapped to API stubs that validate the format of the input data supplied by the Issuer. Moreover, sandbox APIs are designed to return a successful response for a limited set of sample data.

The Sandbox environment allows to validate your connectivity to Bill Pay as well as the format of the requests that your implementation sends to Bill Pay. It is recommended to test the full functionality of the RPPS Bill Payment Validator Service in Sandbox before moving to the MTF environment.

See [API Reference](https://developer.mastercard.com/bill-payment-validator/documentation/api-reference/index.md) to get sample sandbox data.

<br />

Once you've completed testing in Sandbox, you are ready to add production key for [Production Testing](https://developer.mastercard.com/bill-payment-validator/documentation/tutorials-and-guides/production-key/index.md)