Software Engineer III

CSI PROFESSIONALS
Valparaiso, IN
Job Description
Role Overview

We are seeking a highly skilled Software Engineer with extensive experience in ACI Postilion Realtime SDK, payment network integrations, and transaction switching. The ideal candidate will be responsible for designing, developing, and supporting high-volume payment processing solutions that integrate with card networks, EFT networks, core banking systems, and third-party payment services.

What You Will Do

Design, develop, and maintain custom applications using Postilion Realtime SDK, develop new nodes using Rest API, routing logic, and authorization modules within the Postilion platform, and support network certifications and transaction testing activities.

Why It Might Be a Fit

The ideal candidate will have strong expertise in electronic payments, ISO 8583 messaging, transaction routing, authorization processing, network connectivity, and end-to-end payment transaction lifecycle management.

Requirements

  • 5+ years of software development experience
  • 5+ years of hands-on experience with ACI Postilion
  • Strong experience developing solutions using Postilion Realtime SDK
  • Experience supporting production payment switching environments
  • Proven experience integrating payment networks and third-party processors
  • Strong understanding of ISO 8583 transaction messaging
  • Experience with ATM transaction processing
  • Experience with POS transaction processing
  • Experience with debit and credit card payment systems
  • Experience with authorization and settlement flows
  • Programming experience in Java
  • Proficiency with SQL and relational databases
  • Strong TCP/IP networking knowledge
  • Experience with REST APIs, Web Services, and socket-based integrations
  • Familiarity with Windows and Linux server administration
  • Experience integrating with Visa, Mastercard, Pulse, NYCE, STAR, or similar networks
  • Knowledge of acquiring and issuing transaction flows
  • Understanding of network certification processes
  • Experience troubleshooting network connectivity and transaction routing issues
  • Familiarity with payment settlement and reconciliation processes

Benefits

  • Comprehensive range of benefits
  • Eligibility for incentive awards based on both individual and business performance
  • Competitive salary
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