> ## Documentation Index
> Fetch the complete documentation index at: https://docs.opigno.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Consumer User Authentication

The Opigno Enterprise API authorization system implements a two-level authentication model:

[**<u><u>Client’s platform </u></u>**](/OpignoEnterpriseAPI/GlossaryAndAppendices)– Uses the OAuth 2.0 protocol with the Client Credentials grant type to verify the authenticity of the client's server application.

**User Context** – Provided via a UUID passed in the `Opigno-Client-UUID` header.

### **Client Authentication**

The client application can authenticate using OAuth2 Client Credentials for server-to-server communication, such as when integrating the [<u>Opigno Connect</u>](/OpignoEnterpriseAPI/GlossaryAndAppendices) module with a Drupal site.

All GraphQL queries must include authorization data in the header, as explained in the [<u>OAuth2 Authorization</u>](/OpignoEnterpriseAPI/OAuth2Authorization).