Online payment authentication is crucial for preventing fraud and ensuring secure transactions in fintech, e-commerce, and SaaS platforms. It serves as a vital defense against unauthorized transactions, chargebacks, and regulatory issues by confirming the validity of both the payment method and the identity of the user. Common methods include multi-factor authentication, biometric checks, and device-based approaches, which help verify users through a combination of something they know, have, or are. Tokenization and device intelligence further enhance security by replacing sensitive information with unique codes and analyzing device behavior to detect anomalies. Regulatory frameworks like the EU's PSD2 mandate strong customer authentication to prevent fraud, requiring at least two authentication factors. Balancing security and user experience is key, as overly strict measures can deter customers, while lenient ones may invite fraud. Risk-based and adaptive authentication strategies help tailor the level of scrutiny based on transaction risk. Fingerprint, a device intelligence platform, aids payment authentication by identifying devices with high accuracy, providing risk indicators, and ensuring compliance with regulations like PSD2, ultimately reducing friction for legitimate users while blocking fraud.