Payments Modernization Hub

A reference implementation of a modern payments hub designed for banks and fintech organizations.
This project models how large financial institutions can process real time and high-value payments using ISO 20022 standards, microservices-style components, and event-driven workflows.

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1. Overview

This repository demonstrates core building blocks of a next-generation payment system. It includes:

• Real time payment flows (RTP / FedNow style)
• High-value payment and wire processing
• ISO 20022 style parsing and message construction
• Multi-rail routing and orchestration
• Rules, validation, and sanctions-style checks
• Ledger posting and settlement models
• Kafka-like event integration points
• Utility modules for fees, limits, risk scoring, configuration, and more

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2. Architecture Summary

The design follows these principles:

• Modular, domain-driven structure with clearly separated packages
• Rail-specific services for RTP and Zelle style flows
• Event-friendly design supporting stream processing and asynchronous flows
• ISO 20022 compliant components for structured, data-rich messaging
• Extensible architecture allowing for additional rails, clearing networks, or custom business logic

Architecture diagrams are located in the diagrams directory.

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3. Key Components

Core Processing

PaymentEngine — Processes payment requests, applies business rules, and determines success or failure.
PaymentOrchestrator — Coordinates payment routing and execution logic across different payment rails.

ISO 20022 Helpers

Pacs008Parser — Parses simplified ISO 20022 XML messages to extract fields like EndToEndId.
Pacs002Builder — Builds basic acknowledgment messages for payment status updates.

RTP and Zelle Services

RtpLimitService, RtpFeeCalculator — Implements logic for payment limits and fee calculations.
ZelleEnrollmentService, ZelleAliasValidator, ZelleLimitService — Handles alias verification, account enrollment logic, and daily limit enforcement.

Risk, Security, and Rules

FraudDetectionEngine — Basic rule-based fraud detection logic.
VelocityCheckService — Monitors transaction velocity and raises alerts when thresholds are exceeded.
FeeRuleEngine, CutoffTimeEvaluator, CountryRiskScorer — Example modules for fee policies, cut-off time checks, and country-based risk scoring.

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4. Getting Started

Requirements

• Java 17 or later
• Maven or Gradle (optional)
• An IDE such as IntelliJ IDEA or VS Code

Clone the Repository

git clone https://github.com/RahulAutade2288/payments-modernization-hub.git cd payments-modernization-hub

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5. Use Cases

This repository can be used for a wide range of learning, demonstration, and engineering scenarios, including:

• Learning payment hub design fundamentals such as orchestration, routing, and rule evaluation
• Teaching banking and ISO 20022 messaging concepts with hands-on Java examples
• Demonstrating payment system architecture during technical interviews or architecture reviews
• Prototyping new payment rails or clearing systems using modular and extensible components
• Supporting research or EB-1A documentation by showcasing technical design and implementation work
• Showcasing real-world financial technology engineering skills for career, portfolio, or academic use

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6. Roadmap & Future Enhancements

Planned improvements and future extensions include:

• Spring Boot wrappers to expose RESTful APIs for payment initiation and status retrieval
• Real Kafka producers and consumers to simulate event-driven clearing and settlement
• Expanded ISO 20022 coverage including additional message types such as pacs, pain, and camt series
• Full end-to-end payment flow simulations covering initiation, validation, routing, posting, settlement, and notifications
• Comprehensive unit and integration tests for reliability and regression coverage
• Enhanced logging, monitoring, and error-handling frameworks for production-grade observability

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7. Author

Rahul Autade

• Senior Technology Manager and architect specializing in payments modernization, real time payments, ISO 20022, and financial technology engineering.
• Portfolio: https://rahulautade2288.github.io/

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8. Project Structure

payments-modernization-hub
│
├── README.md
├── src
│ ├── main
│ │ ├── java
│ │ │ └── com.payments.modernization
│ │ │ ├── account
│ │ │ ├── api
│ │ │ ├── auth
│ │ │ ├── clearing
│ │ │ ├── config
│ │ │ ├── core
│ │ │ ├── crypto
│ │ │ ├── exceptions
│ │ │ ├── iso20022
│ │ │ ├── kafka
│ │ │ ├── ledger
│ │ │ ├── model
│ │ │ ├── notifications
│ │ │ ├── rtp
│ │ │ ├── rules
│ │ │ ├── security
│ │ │ ├── settlement
│ │ │ ├── simulation
│ │ │ └── zelle
│ └── resources
│ └── application.yml
│
├── diagrams
└── docs


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