> For the complete documentation index, see [llms.txt](https://docs.facephi.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.facephi.com/docs.facephi-en/rest-api/identity-api/identity-api-reference/authentication.md).

# Authentication

The Authentication API provides services for Identity Verification of previously registered users, using facial and voice biometrics.

#### Available services

* **Authenticate User**: Validates the liveness check and facial Authentication by comparing the Biometric Template stored during Onboarding with a current tokenized image.
* **Authenticate User V2**: Improved Version of the facial Authentication service with liveness check validation and Biometric Template comparison.
* **Update User Template**: Allows updating the Biometric Template associated with a user, synchronizing the stored template with a newly registered template.
* **Delete Users**: Allows batch deletion of users registered in the Authentication system.
* **Voice Authentication**: Authenticates a user using their voice, comparing an audio file with a previously registered voice template.