What is the Profile API and how is it used in real-time personalization?

The Profile API allows external systems to query the Unified Profile of an individual in real time using a known identifier (email, phone, loyalty ID, or Salesforce Contact ID). Use cases:

1. Experience Cloud — an LWC component on a community page calls the Profile API to retrieve the visitor's Calculated Insights (e.g., lifetime value, product preferences) and render personalized content.
2. Einstein Personalization — the real-time decision engine calls the Profile API to evaluate segment membership and recommend the next best action or offer.
3. Custom Applications — any web app or mobile app can call the Profile API via OAuth 2.0 to build personalized in-session experiences. The Profile API response includes profile attributes, contact points, segment memberships, and computed insights, making it the single source of truth for real-time personalization decisions.