> For the complete documentation index, see [llms.txt](https://help.citrusad.com/retail-media-interface/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://help.citrusad.com/retail-media-interface/partner/partner-api-authentication/authenticating-requests.md).

# Authentication requests

Epsilon Retail Media uses the User Key method for authenticating API requests. You can also retrieve the User Key through the [Retrieve user key](/retail-media-interface/partner/partner-api-authentication/getuserkey.md) API, which serves as an alternate method to obtain the User Key from user settings. The Retrieve user key API allows partners to generate an authentication key by providing a valid username and password.

## User key

In the Epsilon Retail Media platform, advertisers can find their user key in the **User Settings** section. This key is unique to a **user** level, and can be integrated into your application to manage authentication with the Epsilon Retail Media system.

<figure><img src="https://110176934-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FyPijakfWdNW5OjxjMGoY%2Fuploads%2Fgit-blob-79e88bc374f562fff00d476665de044ec39bd48f%2Fuserkey1.png?alt=media" alt="" width="100%"><figcaption></figcaption></figure>

{% hint style="warning" %}
This user key is not representative of a team, and should not be treated as such.
{% endhint %}

### Authentication flow diagram

<figure><img src="https://110176934-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FyPijakfWdNW5OjxjMGoY%2Fuploads%2Fgit-blob-509f551aa6558cf3a766eb2463ee7ff223534532%2FUser_key_flow.png?alt=media" alt="User key flow.png" width="100%"><figcaption></figcaption></figure>


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