Senior Java Software Engineer (Payments)

This is a long term contract opportunity. Candidates MUST be local to the United States. This role is not open to C2C, OPT, or any Visa consideration. No vendor support of any king allowed.Senior Java Payments EngineerPosition OverviewWe are seeking an experienced Senior Java Payments Engineer to design, develop, and support high-volume payment processing solutions within the banking and financial services industry. The ideal candidate will bring deep expertise in Java backend development, middleware, APIs, payment switches, and payment messaging, with strong hands-on experience working with Postilion highly preferred.This role will be responsible for developing and integrating payment solutions that support debit card, credit card, and banking transactions, while ensuring solutions are scalable, secure, reliable, and aligned with industry standards.Key ResponsibilitiesDesign, develop, enhance, and maintain backend and middleware applications using Java within high-volume payment processing environments.Develop and integrate RESTful APIs, middleware services, SDKs, and other payment-related components.Work extensively with payment switches, with a strong preference for hands-on Postilion experience.Design and support payment transaction flows involving debit cards, credit cards, banking applications, and electronic payment systems.Develop, configure, troubleshoot, and integrate solutions utilizing the ISO 8583 messaging standard.Analyze and resolve complex issues across payment applications, middleware, APIs, transaction processing, and system integrations.Collaborate with architects, product teams, business stakeholders, and other engineering teams to translate payment requirements into scalable technical solutions.Participate in system design, development, testing, deployment, production support, and performance optimization.Develop and maintain integrations between payment switches and internal or external banking/payment platforms.Support secure payment processing practices, including card encryption technologies and PCI-related standards.Required QualificationsSenior-level software engineering experience with a strong background in Java development.Expert-level experience with Java backend development, middleware, APIs, and enterprise application development.Strong professional experience within the payments, banking, or financial services industry.Experience supporting debit card, credit card, and/or banking payment systems.Hands-on experience with Postilion or another enterprise payment switch is highly preferred.Strong understanding of ISO 8583 and its application to payment transaction messaging.Experience developing and integrating APIs, middleware services, and payment-related SDKs.Strong understanding of payment transaction processing, integrations, and system architecture.Experience troubleshooting complex production issues within high-volume transaction environments.Strong communication and collaboration skills with the ability to work across technical and business teams.Ideal CandidateThe ideal candidate is a senior-level Java engineer who combines strong software development expertise with real-world payments experience. A candidate with deep Postilion and ISO 8583 knowledge is particularly valuable. However, strong Java engineers with substantial banking/payments experience who are lighter on ISO 8583 will also be considered, provided they have demonstrated experience working with payment processing systems and integrations.