# Backend URL Configuration

The SDK offers flexibility in configuring the backend URLs for API requests. While it comes with a default set of the backend URLs, you can modify this setup to better align with your application's specific requirements.

## Default URL Behavior

Out of the box, the SDK follows this URL precedence:

1. The Base URL passed programmatically via `Initialize(string baseUri,...)` method. It takes the highest priority.
2. The reserved backend URLs passed programmatically via `Initialize(string baseUri, IEnumerable reserveUris,...)` method.\
   In this case the SDK applies providing reserved backend URLs instead of default set.
3. If only the Base URL was provided the SDK apply default set of the backend URLs like a reserved addresses.

{% hint style="info" %}

* The exact default production URLs are not specified in the SDK documentation.
* The SDK does not include any predefined stage URLs - only production URLs. Use empty collection of reserve URLs to avoid usage predefined PROD reserve addresses
  {% endhint %}

## Customizing Backend URLs

You can override the default production URLs by providing your own set of the backend URLs to `Initialize` method like `Initialize(string baseUri, IEnumerable reserveUris,...)`.

## When to Use Custom Backend URLs

Custom backend URLs are useful in a few scenarios:

* Testing the SDK with stage or development backend environments
* Using backend URLs tailored specifically to your application or project
* Replacing the default production URLs with your own custom fallback options
