> For the complete documentation index, see [llms.txt](https://docs.takionapi.tech/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.takionapi.tech/px-web.md).

# Perimeter X Web

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**Trial and plan access is gated.** A PerimeterX bypass can be abused for fraud, so trial access is not automatic, and PXHC additionally requires your key to be whitelisted for the service. Please contact us on [Discord](https://takionapi.tech/discord) or [via mail](mailto:sales@takionapi.tech) , we'll need to verify your business first.
{% endhint %}

{% hint style="info" %}
Check our example bundles in order to validate your implementation against our validate ones, with correct headers order, TLS and flow from our [**Github repo**](https://takionapi.tech/examples)
{% endhint %}

## **What is PerimeterX Web?**

PerimeterX, now HUMAN Security, builds a risk score from a device fingerprint and a deep telemetry analysis of your behavior, gathered through a series of encrypted posts as you use the page. It sets a `_px3` cookie that carries your trusted session. Its challenges rotate constantly, which is what makes it hard to keep up with by hand.

The web trust lives in the `_px3` cookie. Mobile apps running the PerimeterX SDK carry the same trust in an `x-px-authorization` header set instead (see [PerimeterX Mobile](/px-mobile.md)).

## **How to Detect if a website is Using PerimeterX**

If a site sets a `_px3` cookie, it is running PerimeterX / HUMAN. When traffic looks automated it serves a press-and-hold ("press and hold to confirm you are human") captcha before granting acces, that hold captcha is handled by the [Hold Captcha](/pxhc.md) flow. Common fingerprints:

* A `_px3` cookie on the response.
* A press-and-hold captcha page instead of the content.
* Collector posts to `*.perimeterx.net` or `*.px-cloud.net`.

<figure><img src="/files/r1bZPp8VEwYCTuhlQO5X" alt=""><figcaption></figcaption></figure>

### **Example of PerimeterX-Protected Websites**

Some applications known to use PerimeterX for websites protection include:

| [Zillow](https://www.zillow.com/)         |
| ----------------------------------------- |
| [Walmart](https://www.walmart.com/)       |
| [PrizePicks](https://www.prizepicks.com/) |
| [TextNow](https://www.textnow.com/)       |
| [SkyScanner](https://www.skyscanner.com/) |
| [StockX](https://stockx.com/)             |
| [Grubhub](https://www.grubhub.com/)       |
| [Fanatics](https://www.fanatics.com/)     |
| [Crunchbase](https://www.crunchbase.com/) |

## Our API <a href="#our-api" id="our-api"></a>

Takion automates the whole challenge flow and returns the `_px3` cookie alongside any other generated one during the resolution, so you can access protected sites without solving anything yourself. Continue to the reference