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/Agile 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.

📌 Java Developer | Payment Aggregation / Merchant Payments (Chennai)
🏢 ThreatXIntel
📍 Chennai