Sardine Chargeback Guarantee is a fraud prevention service that provides guaranteed risk decisions for card transactions in real-time. The service evaluates transaction information submitted via API and returns risk decisions with a guarantee, handling the financial liability for fraudulent chargebacks. The platform operates through a four-step process: merchants submit card transaction information via API, Sardine evaluates transactions in real-time and returns guaranteed risk decisions, merchants provide authorization and settlement feedback to optimize performance, and Sardine handles dispute management, evidence preparation, and merchant reimbursement for guaranteed transactions. The service aims to reduce false positives through accurate risk scoring, allowing businesses to approve more legitimate customers while maintaining low fraud rates. It provides predictable fraud costs by guaranteeing performance, reducing variable fraud expenses that complicate forecasting. The platform also reduces operational overhead by managing fraud detection, risk decisioning, and dispute management on behalf of merchants. Sardine Chargeback Guarantee integrates with other fraud prevention capabilities including device intelligence, behavior biometrics, identity fraud detection, bank account validation, and KYC/KYB onboarding flows. The service is designed for merchants processing card transactions who want to transfer chargeback risk while maintaining high approval rates.