# Cookie Sync

## Overview

Cookie syncing allows Nexx360 to share user identifiers with demand partners, improving match rates and bid performance. There are two approaches: passing IDs directly in the bid request, or using Nexx360's cookie sync endpoints.

## ID Sharing via Bid Request

When a seller is already synced with third-party partners, they can share user IDs through the `user.ext.eids` field in the OpenRTB request.

### EID Format

```json
{
    "source": "adnxs.com",
    "uids": [
        {
            "id": "6193521930111213563"
        }
    ]
}
```

## Cookie Sync Endpoints

Nexx360 provides two cookie sync endpoints that DSPs can use to sync user IDs with Nexx360.

### Redirect Endpoint

```
GET https://fast.nexx360.io/usermatchredir/redirect
```

This endpoint reads the Nexx360 user cookie (`xxuid`), and if a redirect URL is provided, replaces the `$UID` macro with the user ID and redirects the user to that URL.

#### Query Parameters

| Parameter      | Required | Description                                |
| -------------- | -------- | ------------------------------------------ |
| `gdpr`         | No       | GDPR applies flag (`0` or `1`)             |
| `gdpr_consent` | No       | TCF consent string                         |
| `us_privacy`   | No       | US Privacy (CCPA) string                   |
| `gpp`          | No       | Global Privacy Platform string             |
| `gppsid`       | No       | GPP Section ID                             |
| `redir`        | No       | URL-encoded redirect URL with `$UID` macro |

#### Example

```
https://fast.nexx360.io/usermatchredir/redirect?gdpr=0&redir=https%3A%2F%2Fdsp.com%2Fsync%3Fuid%3D%24UID
```

This will redirect the user to `https://dsp.com/sync?uid=<xxuid>` where `<xxuid>` is the Nexx360 user ID.

#### Behavior

* If GDPR consent is required but not valid, returns `200` with no sync.
* If no `xxuid` cookie is present, returns `204`.
* If no `redir` parameter is provided, the cookie is refreshed and returns `204`.
* If a valid `redir` is provided, replaces `$UID` with the user ID and responds with a `302` redirect.
* Only the `$UID` macro is supported. Other macros will return a `400` error.

### Iframe Endpoint

```
GET https://fast.nexx360.io/usermatchredir/iframe
```

This endpoint returns an HTML page that can be loaded in an iframe. The page embeds the Nexx360 user ID and privacy parameters, then executes a cookie sync script that handles syncing with multiple demand partners.

#### Query Parameters

| Parameter      | Required | Description                    |
| -------------- | -------- | ------------------------------ |
| `gdpr`         | No       | GDPR applies flag (`0` or `1`) |
| `gdpr_consent` | No       | TCF consent string             |
| `us_privacy`   | No       | US Privacy (CCPA) string       |
| `gpp`          | No       | Global Privacy Platform string |
| `gppsid`       | No       | GPP Section ID                 |
| `redir`        | No       | URL-encoded redirect URL       |

#### Example

```html
<iframe src="https://fast.nexx360.io/usermatchredir/iframe?gdpr=0" style="display:none"></iframe>
```

#### Behavior

* Returns an HTML page with a `window.cookieSyncRedir` object containing the privacy config and `xxuid`.
* If GDPR consent is required but not valid, the page is returned without the `xxuid`.
* The embedded script handles syncing with demand partners automatically.

## Supported Sync Partners

| Partner                 | Cookie Domain      |
| ----------------------- | ------------------ |
| AdaptMX                 | a-mo.net           |
| Adform                  | adform.net         |
| Adot                    | adotmob.com        |
| Adyoulike               | omnitagjs.com      |
| Appnexus (Xandr)        | adnxs.com          |
| Bidswitch               | bidswitch.net      |
| Bliink                  | bliink.io          |
| Colossus                | colossusssp.com    |
| ConnectAd               | connectad.io       |
| Conversant              | dotomi.com         |
| e-Planning              | e-planning.net     |
| Freewheel               | stickyadstv.com    |
| GumGum                  | gumgum.com         |
| Improve (Azerion)       | 360yield.com       |
| Index Exchange          | casalemedia.com    |
| Media.net               | media.net          |
| NextMillennium          | nextmillmedia.com  |
| OneTag                  | onetag-sys.com     |
| OpenX                   | openx.net          |
| Outbrain                | zemanta.com        |
| Pubmatic                | pubmatic.com       |
| PulsePoint              | contextweb.com     |
| RichAudience            | richaudience.com   |
| Rise                    | yellowblue.io      |
| RTB House               | creativecdn.com    |
| Rubicon (Magnite)       | rubiconproject.com |
| Sharethrough            | sharethrough.com   |
| Smaato                  | smaato.net         |
| Smartadserver (Equativ) | smartadserver.com  |
| Smilewanted             | smilewanted.com    |
| Triplelift              | 3lift.com          |
| The Trade Desk          | adsrvr.org         |
| Yieldlab                | yieldlab.net       |


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# Agent Instructions: 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:

```
GET https://developer.nexx360.io/integration-methods/openrtb/cookie-sync.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

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.