> For the complete documentation index, see [llms.txt](https://docs.vida.id/identity-stack/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.vida.id/identity-stack/authentication/authentication-factors/biometric-device-selfie-id/integration-methods/selfie-id-api/api/api-reference/transaction-completion.md).

# Transaction Completion

Transaction completion marks the final step in the user authentication or provisioning process. This request is sent to the follow-up URI received as part of the response from the Transaction Initiation Request. The user agent or client presents the challenge response to the VIDA Authentication Server to complete the authentication or provisioning transaction. 

VIDA server responds with the access token in case of successful authentication.