Java Developer Payment Aggregation / Merchant Payments

Company Description

ThreatXIntel is a growing Cybersecurity, IT Staffing, and Consulting company delivering end-to-end technology and security solutions.

We are hiring for our corporate client. ThreatXIntel is the official hiring partner for this requirement.

About the Role

We are looking for a Java Developer with 4–6 years of experience in Payment Aggregation, Payment Gateway, Merchant Acquiring, UPI, or merchant payment systems.

The ideal candidate should have strong hands-on experience with Java, Spring Boot, REST APIs, microservices, and practical exposure to online/offline merchant payment flows, UPI, QR, POS, Soundbox, refunds, reversals, callbacks, settlement, and reconciliation.

Key Responsibilities

• Design, develop, and maintain backend payment applications using Java and Spring Boot.
• Develop and integrate REST APIs for Payment Aggregator and Payment Gateway platforms.
• Implement end-to-end merchant payment transaction flows.
• Work with UPI, Static/Dynamic QR, POS, Soundbox, online checkout and payment gateway integrations.
• Develop 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 partners.
• Build secure, scalable and high-volume transaction processing APIs.
• Troubleshoot production issues and analyse transaction logs/API responses.
• Handle transaction failures, timeouts, duplicate transactions and idempotency.
• Participate in code reviews, solution design, SIT/UAT and production releases.
• Support performance testing, monitoring and production troubleshooting.
• Follow applicable payment security, coding and compliance standards.

Required Technical Skills

• Strong hands-on Core Java.
• Java 8/11/17+.
• Spring Boot, Spring MVC, REST APIs.
• Microservices architecture.
• Third-party API integration.
• SQL and relational databases — MySQL/Oracle.
• JSON, XML, HTTP/HTTPS and API authentication.
• Git and CI/CD.
• Application logging, monitoring and troubleshooting.
• AWS/cloud knowledge is preferred.
• Knowledge of asynchronous processing, messaging and event-driven architecture is an advantage.

Mandatory Payment Domain Experience

Practical experience in one or more of:

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

Preferred Knowledge

• UPI transaction lifecycle.
• Merchant acquiring ecosystem.
• QR and Soundbox transaction architecture.
• Payment switch/processor integrations.
• Idempotency and duplicate transaction handling.
• Fraud/risk checks.
• PCI-DSS and payment security.
• Encryption, masking and secure payment/customer data handling.

Work Mode: Onsite

Employment Type: Contract

Experience: 4–6 Years

Interested candidates can apply through LinkedIn with their updated resume.