Constella Identity Fraud Detection API provides API services for detecting and preventing identity fraud through analysis of compromised credentials and email reputation data. The product monitors credentials, session cookies, and PII across surface, deep, and dark web sources to identify fraud indicators. The solution consists of two primary API services: Account Takeover (ATO) Infostealers API and Email Reputation Score API. The ATO API detects compromised emails and credentials from breaches, combo lists, and infostealer campaigns, tracking exposed credentials in real-time. It identifies emails tied to active infections and provides contextual data including breach origins, exposure dates, and geographic metadata. The Email Reputation Score API evaluates incoming email addresses to detect phishing, spoofing, and malicious activity. It identifies fraudulent patterns by uncovering links between email addresses and known malicious sites or activities, assigning dynamic risk scores using AI-powered analysis. The product monitors stolen credentials, session cookies, sensitive documents, and email reputation scores. It detects synthetic fraud indicators by identifying emails created without historical breaches. The APIs are designed for integration into existing fraud prevention systems, security workflows, and threat intelligence platforms. Target industries include identity theft and credit protection services, retail and consumer services, cybersecurity providers (EDR/MDR/XDR), government and law enforcement, and financial services.