To use Yva.ai API you should firstly create Integration API source in Manage sources tab and get access_token.

Assign access_token to the HTTP header as a bearer token, as shown in the following example.

POST https:/eeu.yva.app/api/integration/v2.0/sources/chat/messages
Authorization : Bearer {access_token}
CODE

You can find all the information about Yva.ai API here: https://api-docs.yva.ai/