Which API supports username and password authentication?

• A. SOAP API
• B. REST API
• C. Web App
• D. Public App

Answer: (A)

In Marketing Cloud, credential-based login is provided by the SOAP API through an Authenticate call that uses a user’s username and password to establish a session. This makes the SOAP API the option that directly supports username/password authentication, returning a session token you use for subsequent API calls. The REST API, on the other hand, relies on OAuth 2.0—you obtain an access token via an OAuth flow rather than sending a username and password directly. Web App and Public App aren’t APIs or authentication methods themselves; they’re app types that typically rely on OAuth for access. So, for direct username/password login, the SOAP API is the correct choice.