Scaling 3DS Card Authentication for Air India

Large travel merchants have checkout flows where authentication, gateway routing, and transaction status must align cleanly. A failure in handoff can directly affect customer conversion and operational support.

This case study is intentionally generalized to respect confidentiality while still showing the architecture thinking behind the work.

The integration needed to introduce UAS into the Euler transaction flow, orchestrate card authentication, and keep transaction state explainable across provider boundaries.

The system had to support merchant-specific behavior without creating a one-off path that would be difficult to monitor or reuse.

Payment correctness and secure data handling were non-negotiable.

The flow needed low-latency provider interactions and clear timeout behavior.

Merchant-specific configuration had to stay explicit and auditable.

Provider failures needed fallback paths, status clarity, and operational visibility.

The implementation needed load testing and production readiness before rollout.

Led development across API contract design, authentication orchestration, data pipeline touchpoints, load testing, and rollout readiness.

Kept the implementation high-level and reusable enough to inform future merchant authentication onboarding.

Modeled the flow as explicit transaction stages so authentication state, gateway handoff, and issuer response could be reasoned about independently.

Defined API contracts between checkout-facing systems, Euler, and authentication components with validation, status mapping, and failure semantics.

Added data pipeline touchpoints for downstream analytics and operational monitoring without exposing sensitive card details.

Prepared load testing around realistic authentication paths and failure cases before production enablement.

A merchant-specific path could have shipped faster, but a reusable integration shape reduced future onboarding risk.

More detailed status modeling added implementation work, but made operations and debugging materially safer.

The authentication flow supported 250K+ monthly card transactions.

The work improved confidence in production readiness for merchant-scale 3DS flows and created reusable patterns for future integrations.

The quality of a payment integration is often decided by its failure semantics and observability, not just happy-path API calls.

Clear contracts let teams move faster because they reduce guesswork during rollout and incident response.