Principal .NET Software Engineer - Cloud Payments Platform

Versapay is a company that automates accounts receivable to enhance cash flow and business growth. They are seeking an experienced .NET Principal Software Engineer to modernize their payments infrastructure, improve scalability and security, and design new distributed services.

Responsibilities:

• Own and evolve core payment services for online (CNP), device-based EMV (CP), digital wallets (e.g., Apple Pay, Google Pay), and payment facilitator/orchestration flows
• Modernize and improve existing components into more cloud-native, distributed architectures using containers on AWS/Azure
• Own and extend end-to-end payment workflows: authorization, capture, void, refund, tokenization, clearing, funding, settlement, and multi-source reconciliation
• Expand capabilities for international payments, including multi-currency and cross-border flows
• Integrate with payment service providers (PSPs), EMV card readers, and device SDKs using secure, standards-based messaging
• Improve and maintain CI/CD pipelines in GitHub Actions (automated builds, tests, security scans, packaging, deployments)
• Design and evolve test automation strategy, covering domain-level logic, API contracts, and integration with external processors and devices
• Strengthen platform reliability through observability (metrics, logs, traces), fault-tolerant design, and automated operational workflows
• Partner with Product, Security, Compliance, and Operations to deliver features that balance customer experience, regulatory requirements, risk, and operational robustness
• Mentor engineers, lead design and architecture discussions, and influence the long-term strategy for the payments platform

Requirements:

• Significant experience (typically 10+ years) of professional engineering with expert proficiency in C#, .NET, and SQL
• Deep experience in payments: online payments, EMV device-based transactions, digital wallets (e.g., Apple Pay, Google Pay), PayFac/orchestration flows, bank account rails (ACH/EFT), and international/multi-currency payment flows
• Proven ability to modernize production financial systems into cloud-native, distributed architectures
• Familiarity with monitoring and observing distributed systems using modern observability tooling
• Proven ability to work cross-functionally with Product, Security, Compliance, and Operations, and to represent engineering effectively to non-technical stakeholders
• Experience using AI-assisted development tools to enhance productivity and code quality
• Deep Hands-on Experience With Several Of The Following: ISO 8583 transaction messaging, ISO 20022 data models and payment messaging, DUKPT key-management and secure device cryptography, Hardware Security Modules (HSMs) and secure key lifecycle, EMV payment kernels and card/device authentication flows
• Strong Knowledge Of: Modern API and integration design (RESTful services), asynchronous messaging/queueing, caching, event-driven architecture, high-availability patterns, AWS or Azure, containerization, orchestration, and CI/CD automation, PCI-DSS, encryption, tokenization, key-rotation, and secure coding principles
• Experience with multi-region cloud architecture and distributed data patterns
• Experience with modern UX/front-end development (e.g., JavaScript/TypeScript)