Backend Engineer
Real-Time Fraud Risk Scoring Across Transaction Lifecycle
A sanitized view of integrating Accertify and Feedzai into transaction lifecycle risk scoring with merchant-configurable controls.
Details are intentionally generalized to respect confidentiality.
- Timeline
- 2025
- Domain
- Risk scoring, provider integration, merchant policy controls
- Impact
- Integrated fraud-risk providers across pre-transaction, post-transaction, and pre-refund stages.
Architecture
Sanitized System Flow
The diagram shows the major responsibility boundaries without exposing proprietary internal implementation.
Fraud Risk Pipeline
Integrated Accertify and Feedzai flows, risk policy controls, country/currency lists, lifecycle scoring, and feedback handling.
Context
Fraud-risk systems sit on the critical path for some transactions and on operational feedback paths for others.
The architecture described here is generalized and avoids confidential provider or platform internals.
Problem
The platform needed risk checks before transactions, after transactions, and before refunds, with provider-specific integrations and merchant-configurable controls.
Risk decisions needed to influence flow behavior while remaining observable and explainable.
Constraints
Risk calls could not make the payment path fragile.
Provider outages needed safe handling and clear policy behavior.
Country and currency blacklist/whitelist controls had to remain merchant-configurable.
Refund and chargeback feedback needed to improve downstream operational insight.
My Role
Built backend integrations and lifecycle scoring paths for Accertify and Feedzai use cases.
Implemented merchant-configurable controls and feedback flows across transaction and refund scenarios.
Technical Design
Separated policy evaluation from provider integration so merchant controls and provider decisions could be reasoned about independently.
Supported pre-transaction, post-transaction, and pre-refund scoring with stage-specific request shape and response mapping.
Added feedback handling for failure outcomes, refund signals, and chargeback-related updates.
Made country and currency blacklist/whitelist behavior explicit in the risk decision path.
Tradeoffs
Running risk checks in more lifecycle stages improved coverage, but required careful latency and failure handling.
Merchant configurability increased surface area, but gave operators the control needed for real-world risk policies.
Impact
Expanded fraud-risk coverage across transaction and refund lifecycle stages.
Improved merchant control over risk posture through configurable country and currency policies.
What I learned
Risk integrations are only useful when their decisions are explainable and their failures are bounded.
Policy design matters as much as provider connectivity.