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

# POST /interstitial

Solve a DataDome interstitial device check. You fetch the interstitial page from the target, hand its HTML and the device link to this endpoint, and replay the returned payload from your own transport.

|            |                                                        |
| ---------- | ------------------------------------------------------ |
| Endpoint   | `POST https://api.vsat.dev/interstitial`               |
| Auth       | `Authorization: Bearer <token>`                        |
| Returns    | `{ ok, payload, headers }`                             |
| TypeScript | `vsat.interstitial({ userAgent, deviceLink, html })`   |
| Python     | `vsat.interstitial(userAgent=…, deviceLink=…, html=…)` |

## When you get one

A `403` whose body carries an inline `dd={'rt':'i', …}` object is an interstitial (its script is `i.js`). Keep two things from that `403`: the `datadome` cookie it sets, and the blocked URL (you replay it as the `referer`).

## Flow

1. **GET the target** with your transport. A `403` + `dd={'rt':'i', cid, hash, …}` is the challenge.
2. **GET the interstitial page** at `https://geo.captcha-delivery.com/interstitial/?cid=…` (built from the `dd` object). Save the HTML body.
3. **POST /interstitial** `{ userAgent, deviceLink, html }` to this API. You get back `{ ok, payload, headers }`.
4. **POST the payload** to `https://geo.captcha-delivery.com/interstitial/` with your transport. A `200 { redirect: … }` with `Set-Cookie: datadome=…` means cleared.
5. **GET the target** again with the fresh `datadome` cookie. You are through.

## Request

| field            | type   | required | meaning                                      |
| ---------------- | ------ | -------- | -------------------------------------------- |
| `userAgent`      | string | yes      | the session User-Agent (Chrome)              |
| `deviceLink`     | string | yes      | the interstitial URL from the challenge      |
| `html`           | string | yes      | the interstitial page body you GET in step 2 |
| `ip`             | string | no       | your egress IP (geo)                         |
| `country`        | string | no       | geo hint                                     |
| `acceptLanguage` | string | no       | geo hint                                     |

## Response

```json
{ "ok": true, "payload": "<form body to POST back>", "headers": { } }
```

* `payload`: POST this verbatim to `https://geo.captcha-delivery.com/interstitial/`.
* `headers`: replay these on your request to the target. Do not hardcode them.

{% hint style="danger" %}
Use the same User-Agent, TLS fingerprint, IP and header order for every step. The `cid` is IP-bound: a payload built for one exit and spent from another is rejected. This is the most common integration mistake.
{% endhint %}

## Raw HTTP

```http
POST /interstitial HTTP/2
Host: api.vsat.dev
Authorization: Bearer <token>
Content-Type: application/json

{ "userAgent": "...", "deviceLink": "https://geo.captcha-delivery.com/interstitial/?cid=...", "html": "<the page you GET>" }
```

```json
{ "ok": true, "payload": "...", "headers": { } }
```


---

# Agent Instructions
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## Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter:

```
GET https://docs.vsat.dev/endpoints/interstitial.md?ask=<question>&goal=<endgoal>
```

`ask` is the immediate question: it should be specific, self-contained, and written in natural language.
`goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal.

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Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.