> For the complete documentation index, see [llms.txt](https://docs.pay.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.pay.io/api-reference/core-concepts/request-structure.md).

# Request Structure

### Request URL structure <a href="#request-url-structure" id="request-url-structure"></a>

Pay.io APIs use a straightforward URL naming convention, consisting of two parts, a **base URL** and **endpoint path**.

#### Base URL for API requests in staging environment <a href="#base-urls-for-api-requests" id="base-urls-for-api-requests"></a>

<pre><code><strong>https://gateway.stage.pay.io/
</strong></code></pre>

**Request structure example**

Structure

```
https://{base-url}/{endpoint-path}
```

Example full request URL for staging environment

```
https://gateway.stage.pay.io/v1/merchant/currencies
```

***

### Required Headers

* `X-API-Key`: Your unique API key obtained from your account settings in Merchant Console or provided by support team.
* `X-API-Nonce`: A unique identifier (UUID) for each request to prevent replay attacks. See [Creating a Merchant Signature (nonce)](/api-reference/core-concepts/authorisation.md#creating-a-merchant-signature) guide for more.&#x20;
* `X-API-Signature`: Signature generated using **RSA-SHA256**. See more in [Authorisation](/api-reference/core-concepts/authorisation.md#creating-a-public-and-private-key) guide.&#x20;


---

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