Java Developer | Payment Aggregation / Merchant Payments

ThreatXIntel; Chennai District; On-site; INR 1,200,000 - 2,200,000; Full time

Job summary

ThreatXIntel is seeking an experienced Java Backend Developer with 4 to 6 years of hands-on experience in Payment Aggregation, Payment Gateway, UPI, and merchant payment systems. The role focuses on building scalable backend services for high-volume payment processing.

You will design and implement REST APIs, microservices, and secure integrations with banks and payment providers, handling transaction flows, settlements, and reconciliation, while ensuring reliability, testing, and production

Qualifications

• Hands-on Java development with Spring Boot and REST APIs.
• Experience in payment integrations and microservices.
• Solid SQL skills and relational databases (MySQL/Oracle).

Responsibilities

• Design, develop, and maintain backend applications using Java and Spring Boot.
• Develop and integrate REST APIs for PA/PG platforms.
• Implement end-to-end online and offline merchant payment flows.
• Integrate with banks, UPI providers, and third-party payment services.
• Develop merchant onboarding and transaction processing services.
• Implement payment status, callbacks, webhooks, refunds, and settlement workflows.
• Ensure security, logging, error handling, and production readiness.
• Troubleshoot production payment failures and perform RCA.

Skills

Core Java

Spring Boot

REST APIs

Microservices

SQL

Git

CI/CD

Logging & debugging

Tools

MySQL

Oracle

JSON/XML

HTTP/HTTPS

Job description

We are looking for an experienced Java Backend Developer with 4 to 6 years of hands‑on experience in Payment Aggregation (PA), Payment Gateway (PG), UPI, and merchant payment systems.

The candidate should have strong experience in Java, Spring Boot, REST APIs, Microservices, SQL, and third-party payment integrations, along with practical understanding of online and offline merchant payment flows such as UPI, QR, POS, Soundbox, refunds, reversals, callbacks, settlement, and reconciliation.

Key Responsibilities

• Design, develop, and maintain backend applications using Java and Spring Boot.
• Develop and integrate REST APIs for Payment Aggregator and Payment Gateway platforms.
• Implement end-to-end online and offline merchant payment flows.
• Work on UPI, Static/Dynamic QR, POS, Soundbox, and payment gateway integrations.
• Develop merchant onboarding and transaction processing services.
• Implement payment status, callback, and webhook processing.
• Implement refund, reversal, settlement, and reconciliation workflows.
• Integrate with banks, UPI providers, payment processors, switches, and third-party payment service providers.
• Develop secure and scalable transaction APIs for high‑volume payment processing.
• Implement transaction lifecycle handling including initiation, authorization, success/failure, timeout, reversal, refund, and settlement.
• Implement appropriate validation, exception handling, logging, and security controls.
• Troubleshoot production payment failures and third‑party integration issues.
• Analyze transaction logs and API responses and perform RCA.
• Participate in code reviews, technical discussions, SIT/UAT, and production releases.
• Support performance testing and production monitoring.
• Follow applicable payment security and coding standards.

Mandatory Technical Skills

• Core Java
• Java 8/11/17+
• Spring Boot / Spring MVC
• REST APIs
• Microservices
• SQL and relational databases
• MySQL / Oracle
• JSON / XML
• HTTP / HTTPS
• API authentication
• Third‑party API integration
• Git
• CI/CD
• Application logging and troubleshooting

Mandatory Payment Domain Experience

Candidates should have hands‑on experience in one or more of:

• Payment Aggregator (PA)
• Payment Gateway (PG)
• Merchant Acquiring
• UPI
• Online payment processing
• Offline merchant payment processing
• Static / Dynamic QR
• POS
• Soundbox
• Payment callbacks / webhooks
• Refunds and reversals
• Settlement and reconciliation
• Merchant onboarding
• Transaction monitoring and failure handling

Preferred Skills

• UPI transaction lifecycle
• Merchant acquiring ecosystem
• QR and Soundbox architecture
• Payment switch / processor integrations
• Idempotency and duplicate transaction handling
• Fraud/risk checks
• PCI-DSS concepts
• Encryption and masking of payment/customer data
• Kafka / messaging / event‑driven architecture
• AWS

Ideal Candidate

The ideal candidate is a Java Backend Developer with genuine production payment-domain experience, capable of developing scalable payment APIs, integrating external payment systems, understanding merchant transaction flows, and troubleshooting transaction-level issues.