# Learn about NVP/SOAP API apps (/api/nvp-soap/apps101)



> **Note:** **Important:** NVP/SOAP is a legacy integration method. We accept new integrations and support existing integrations, but there are newer solutions. If you're starting an integration, [we recommend our latest solutions](/).

The PayPal **NVP/SOAP APIs** provide a set of *application programming interfaces* (APIs) that let you add PayPal payment and transaction functionality to your business applications. The NVP/SOAP APIs offer interfaces that cover all aspects of complex business transactions, including invoicing services, notifications, subscription services, parallel payments, permissions services, and functionality to processes refunds.

## The PayPal development life cycle [#the-paypal-development-life-cycle]

The high-level *development life cycle* is the same for all PayPal services. You incorporate PayPal transaction functionality into applications as follows:

1. Register as a PayPal Developer.
2. Integrate PayPal functionality to your website and mobile applications.
3. Test your PayPal transaction routines.
4. Go live with your application.
5. Maintain and upgrade your app.

## The PayPal developer process [#the-paypal-developer-process]

Here's how you code, test, and deploy your PayPal applications:

1. Use your existing PayPal account to log in to the PayPal [Developer website](/), or create a new account by clicking the **Sign Up** button on this site.
2. Familiarize yourself with how to make PayPal API calls, as described in the [PayPal APIs Getting Started Guide](/api/nvp-soap/gs-PayPalAPIs/).
3. Create virtual sandbox accounts in the sandbox, as described in the [PayPal sandbox Testing Guide](/sandbox-testing/overview).
4. Use the correct [endpoints](/api/nvp-soap/endpoints/) and [credentials](/api/nvp-soap/apiCredentials/) for the environment and operations you're addressing.
5. Refer to the integration documentation for guidance. You can also utilize the [Express Checkout demo site](https://demo.paypal.com/).
6. Test your PayPal routines using the [Sandbox](https://developer.paypal.com/developer/accounts).
7. Take your application Live, as outlined in [Go Live with Your App](/reference/production/).

## Development process and policy docs [#development-process-and-policy-docs]

The following docs address the different phases of development and outline the PayPal developer policies:

* **Policies and guidelines**
  * [PayPal Application Policies and Guidelines](/reference/guidelines/policiesAndGuidelines/)
* **Development process**
  * [PayPal APIs Getting Started Guide](/api/nvp-soap/gs-PayPalAPIs/)
  * [PayPal Sandbox Testing Guide](/sandbox-testing/overview)
  * [Go Live with Your App](/reference/production/)

Visit the [Support page](https://www.paypal.com/support) on the PayPal developer site for support resources and additional information.