SonarQube provides web API to access its functionalities from applications. The web services composing the web API are documented within SonarQube, by URL. You can also access the web API documentation from the top bar in SonarQube:
Administrative web services are secured and require the user to have specific permissions. In order to be authenticated, the user must provide credentials as described below.
This is the recommended way. Benefits are described on the page Generating and using tokens. The token is sent via the login field of HTTP basic authentication, without any password.
Login and password are sent via the standard HTTP Basic fields:
Users who authenticate in the web application through an OAuth provider, for instance, GitHub or Bitbucket, don't have credentials and can't use HTTP Basic mode. They must generate and use tokens.