# Integration and Testing
source: https://developer.mastercard.com/pclo-presentment/documentation/integration-and-testing/index.md

Note: Mastercard supports OAuth 2.0 for authenticating application HTTP requests. Refer to the following resources for guidance and documentation:   

* [Offers for Publishers (Legacy) OAuth 2.0 authentication and first call tutorial](https://developer.mastercard.com/pclo-presentment/documentation/tutorials-and-guides/index.md)
* [Using OAuth 2.0 to Access Mastercard APIs](https://developer.mastercard.com/platform/documentation/authentication/using-oauth-2-to-access-mastercard-apis/)
* [Offers for Publishers (Legacy) Reference Application](https://static.developer.mastercard.com/content/pclo-presentment/uploads/offers-for-publishers-legacy-ref-app.zip): The reference application supports OAuth 1.0a request signing and OAuth 2.0 using FAPI 2.0 with `private_key_jwt` client authentication and DPoP-bound access tokens. Refer to the `README.md` file in the root directory of the application for authentication mode details.
* [Offers for Publishers API](https://developer.mastercard.com/presentment/documentation/release-history/) updated documentation

<br />

Support for OAuth 1.0a authentication remains available.

## Ready to begin testing? {#ready-to-begin-testing}

Tip: We recommend that you begin testing in the sandbox.

Once you have created a project on Mastercard Developers, generated sandbox credentials and received approvals, you can start testing.

### Base URLs for testing: {#base-urls-for-testing}

* Sandbox
* Production

```Sandbox
https://sandbox.api.mastercard.com/loyalty/offers/user-presentment
https://sandbox.api.mastercard.com/loyalty/offers/platform-admin
```

```Production
https://api.mastercard.com/loyalty/offers/user-presentment
https://api.mastercard.com/loyalty/offers/platform-admin
```

## Methods of testing Sandbox/Production: {#methods-of-testing-sandboxproduction-br}

### 1. Reference Application {#1-reference-application}

* Our Spring Boot Reference Application acts as an API client and allows you to integrate different operations.
* For detailed steps, follow our [Reference Application](https://developer.mastercard.com/pclo-presentment/documentation/reference-application-tutorial/index.md) page.

### 2. Postman {#2-postman}

* [Postman Collections](https://www.postman.com/collection/) is an API client that allows developers to test API calls in sandbox and production environments without writing any code. This makes sharing pre-formed API requests with partners extremely easy, and permits partners to run individual API requests or those within a folder or the entire collection.
* For detailed steps, follow the [Postman tutorial](https://developer.mastercard.com/platform/tutorial/use-postman-for-mastercard-apis/).

### 3. Insomnia {#3-insomnia}

* [Insomnia](https://insomnia.rest/) is an open-source API client that developers use to quickly and easily send REST requests to Mastercard APIs. API Consultancy \& Standards developed an [Insomnia Plugin](https://github.com/Mastercard/insomnia-plugin-mastercard) for handling API authentication.
* For detailed steps, follow:
  * [Insomnia tutorial for OAuth 1.0 authentication](https://developer.mastercard.com/platform/tutorial/use-insomnia-rest-client-for-mastercard-apis/)
  * [Insomnia tutorial for Offers for Publishers (Legacy) OAuth 2.0 authentication](https://developer.mastercard.com/pclo-presentment/documentation/tutorials-and-guides/offers-publishers-legacy-auth-first-call-tutorial/index.md)

## Next Steps {#next-steps}

* When you are ready to use the API, refer to the [Reference Application](https://developer.mastercard.com/pclo-presentment/documentation/reference-application-tutorial/index.md) and [API Tutorial](https://developer.mastercard.com/pclo-presentment/documentation/api-tutorial/index.md) sections for information on connecting to Offers for Publishers.
* To learn more about any error codes you receive, refer to [Code and Formats](https://developer.mastercard.com/pclo-presentment/documentation/code-and-formats/index.md).