> ## Documentation Index
> Fetch the complete documentation index at: https://brightdata-ipv6-release.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Web Unlocker API Configuration

> Configure Web Unlocker API with Premium Domains, Geolocation, and advanced settings for custom headers, cookies, and auto-throttling.

## Premium Domains

Some domains are more challenging to unblock than others, so we offer a separate premium pricing tier for [these domains](https://docs.brightdata.com/scraping-automation/web-unlocker/features#current-list-of-premium-domains). Once enabled, the premium price will be reflected in the "Estimated cost" section. \
<Note>Even after enabled, only specific requests to these domains will be priced differently. Requests to other domains will be kept at the default lower tier.</Note>

## Advanced options

### Asynchronous requests

Requests are handled seamlessly in the background, allowing you to collect responses at a later more convenient time via a designated endpoint, increasing stability, flexibility, and efficiency.

Learn more about [asynchronous requests](/scraping-automation/serp-api/asynchronous-requests).

### Custom Web Unlocker API

Override automated headers/cookies and send your own custom values in order to target specific versions of a website.

<Note>
  Enabling **Custom Headers & Cookies** results in the following

  <AccordionGroup>
    <Accordion title="Access to Pre-approved List of Headers/Cookies">
      You'll gain access to a pre-approved list of headers and cookies. You can browse through this list to verify that the required headers and cookies are approved for your target site.
    </Accordion>

    <Accordion title="Send Request for New Headers/Cookies">
      If your required headers or cookies are not on the pre-approved list, you can submit a form to our compliance team for approval. This process involves providing information about the headers/cookies and their necessity. After a short approval process is completed, you will be notified by our compliance team.
    </Accordion>

    <Accordion title="Charging for All Requests">
      Unlike the regular Web Unlocker API logic, which only charges for successful requests, enabling this feature means you'll be charged for 100% of the requests (both successful and failed). This change is due to Bright Data not having full control over the process and its performance.
    </Accordion>
  </AccordionGroup>
</Note>

#### Allow custom Headers & Cookies

1. Access Your Control Panel: Log in to your Bright Data control panel.
2. Select Your Zone: Choose the specific zone where you want to enable this feature.
3. Enable the Feature: Under **Advanced Options**, find and activate the 'Custom headers & cookies' permission within the zone settings.

#### Control Over Auto-Throttling

Web Unlocker API includes an auto-throttling mechanism designed to maintain efficient scraping and performance. This system operates as follows:

<Tabs>
  <Tab title="Automatic Adjustment">
    The system automatically searches for and implements better-performing configurations.
  </Tab>

  <Tab title="Upon Low Success Rates">
    If the success rate for any given target site falls below a certain percentage, the system will begin to throttle requests. This is to avoid wasting resources on configurations that are failing.
  </Tab>

  <Tab title="Customizable Threshold">
    The default threshold for this mechanism is set at 70%.

    However, with the 'Custom headers & cookies' permission enabled, you have the flexibility to adjust this threshold to any percentage you prefer, especially since you'll be charged for all requests regardless of their success.
  </Tab>
</Tabs>