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Payments Fraud
Detection Engine
Cross-account card fraud detection system built in Ruby on Rails. Deployed at scale across 100+ countries at a global fintech payments company.
Production
Ruby on Rails
45% Fraud Reduction
Global Scale
Impact
45%
Reduction in high-risk activations
100+
Countries covered
5
PSPs integrated
15–25
Disputes resolved daily
Overview
Built to address a growing volume of fraudulent account activations using stolen payment cards across a global fintech platform. The system combines multiple data signals at the moment of account activation to compute a risk score — blocking or flagging high-risk accounts before funds are allocated or access is granted.
Designed to be invisible to legitimate users while maximally effective against fraudsters. After deployment, it became the baseline standard for all new account activation decisions.
Tech Stack
Ruby on Rails
PostgreSQL
Redis (caching)
Sidekiq (async jobs)
PSP APIs
IP intelligence APIs
Browser fingerprinting