> ## 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.

# Authentication

> Authenticate PayNext Billing API requests using API keys in the Authorization header.

<Warning>
  **API keys grant full account access.**

  * Copy API keys immediately; they are shown only once on creation
  * Store API keys securely in a secrets manager—never hardcode them in client-side code or commit them to repositories
  * Use separate API keys per environment (development, staging, production)
  * Apply least privilege: restrict each API key's permissions to only what is necessary
</Warning>

PayNext uses **API keys** to authenticate all requests. Manage your keys in the Developers section of the PayNext Dashboard.

***

## How to Authenticate

Include your API key in the `Authorization` header for every request:

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