Senior Software Engineer (.NET/C#, AI/ML,Payment Processing System)

Job Description: The Role:

• We're seeking a Senior Software Engineer with extensive expertise in .NET/C# and fintech experience to join our engineering team. In this role, you'll be responsible for architecting, building, and maintaining critical payment processing systems and integrations that power thousands of businesses. You'll work on challenging problems at scale, from payment gateway integrations to real-time transaction processing, event-driven architectures, and AI-powered payment solutions.
• This is an opportunity to work on production systems that handle billions of dollars in transactions while contributing to a platform that helps small businesses and software companies thrive. You'll leverage cutting-edge technologies including CQRS patterns, Google Cloud Platform, and artificial intelligence to build the next generation of payment infrastructure.

Responsibilities:

• Build scalable payment processing systems using .NET/C# that handle high-volume, mission-critical transactions
• Design and implement CQRS (Command Query Responsibility Segregation) patterns for event-driven payment workflows and real-time data synchronization
• Develop and maintain payment processor integrations with major payment processors
• Build robust RESTful APIs and event-driven microservices that power our payment solutions for ISVs and software platforms
• Integrate AI/ML capabilities into payment systems for fraud detection, risk assessment, transaction optimization, and intelligent routing
• Work on real-time transaction processing with a focus on reliability, security, performance, and data consistency
• Implement PCI-compliant systems ensuring the highest standards of data security and regulatory compliance
• Troubleshoot and resolve technical issues in production payment systems at scale

Qualifications:

• 10+ years of professional software development experience with .NET/C# in production environments
• Strong fintech or payments industry experience, with deep knowledge of payment processor integrations (Stripe, Client, Financial, Worldpay, TSYS, etc.)
• Experience implementing CQRS (Command Query Responsibility Segregation) and event sourcing patterns in production systems
• Hands-on experience with Google Cloud Platform (Google Cloud Platform)
• Experience working with modern AI/ML technologies such as integrating AI models, working with LLMs, implementing AI-powered features, or collaborating with data science teams
• Deep understanding of payment processing workflows including authorization, capture, settlement, refunds, chargebacks, and reconciliation
• Expertise in designing and building RESTful APIs and event-driven microservices for high-traffic, low-latency systems
• Expert knowledge of PCI-DSS compliance and secure payment data handling, tokenization, and encryption
• Strong problem-solving skills with the ability to debug complex distributed payment systems

Nice to Have:

• Experience with CockroachDB or other distributed SQL databases for globally distributed, resilient data storage
• Core and SignalR experience for building real-time web applications and payment notifications
• Background in fraud detection systems or risk management platforms
• Knowledge of network tokenization, 3DS authentication, or Level 2/3 card processing
• Experience with observability tools (Datadog, New Relic, Google Cloud Monitoring)
• Understanding of OAuth 2.0, OpenID Connect, and API security best practices