> ## Documentation Index
> Fetch the complete documentation index at: https://docs.paynext.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Getting Started

> Get up and running with the PayNext Billing API for payment processing, subscription management, and customer billing operations.

Get started with the PayNext Billing API in minutes. Our RESTful endpoints let you process payments, manage subscriptions, and track billing data with enterprise-grade security and reliability.

***

## Prerequisites

Before you begin, ensure you have:

* A PayNext account with API access
* A tool to send HTTP requests (e.g., `curl`, Postman, or fetch)
* Basic understanding of REST APIs

***

## Quick Start

<Steps>
  <Step title="Choose Environment">
    Select the appropriate base URL for your development stage—sandbox for testing or production for live transactions.
  </Step>

  <Step title="Set API Version">
    Include the `X-API-Version` header in all requests to ensure consistent behavior as we release updates.
  </Step>

  <Step title="Authenticate Requests">
    Add your API key to the `Authorization` header to securely access PayNext endpoints.
  </Step>
</Steps>

```bash curl theme={"system"}
curl -X GET 'https://sandbox-api.paynext.com/payments' \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "X-API-Version: 2.0.0"
```

<Check>
  You should receive a JSON response with your payment data or an empty array if no payments exist.
</Check>

***

## API Endpoint Deployments

Choose the correct base URL for your environment:

* **Sandbox**: `https://sandbox-api.paynext.com/`
* **Production**: `https://api.paynext.com`

<Info>
  Use the sandbox environment for all development and testing. Switch to production only when your integration is complete and ready for live transactions.
</Info>

***

## API Versioning

PayNext updates the API regularly as we release new features. To control your integration, pass a `X-API-Version` header in every request.

```bash curl theme={"system"}
curl -X POST 'https://api.paynext.com/payments' \
  -H "Authorization: YOUR_API_KEY" \
  -H "X-API-Version: 2.0.0" \
  -H "Content-Type: application/json" \
  -d '{"amount": 1000, "currency": "USD"}'
```

<Warning>
  Always include the `X-API-Version` header. Without it, your integration may break when new API versions are released.
</Warning>

***

<Tip>
  Start with the Authentication section to secure your API integration, then explore the endpoints that match your payment processing needs.
</Tip>