Senior.NET Engineer

About the role

Our client is building a high-load payment platform designed to process thousands of transactions continuously around the clock. This role offers an to work on complex, distributed backend systems where reliability, scalability, performance, and fault tolerance are critical. You will be involved in developing core components of the platform, ensuring that the system can handle high transaction volumes efficiently and securely. The position requires a focus on designing resilient architectures, optimizing transaction processing, and contributing to a team that values high engineering standards. If you enjoy solving challenging backend problems and building systems that must never fail, this role provides a chance to make a significant impact in the fintech space.

Key facts

What you'll do

• Develop, maintain, and improve the core of the high-load payment platform, ensuring high performance and reliability.
• Design new services and integrations with various payment providers, overseeing the process from architectural planning through to production deployment.
• Enhance transaction processing workflows, routing mechanisms, and webhook infrastructure to support high throughput and fault tolerance.
• Participate actively in architectural discussions, providing technical input on system design choices and scalability strategies.
• Conduct code reviews, share best practices, and help maintain a high standard of engineering quality across the team.
• Collaborate closely with the Connector team, which works with Python and TypeScript, to ensure integration and communication between components.
• Implement and optimize event-driven architecture components, ensuring reliable message delivery and system responsiveness.
• Improve database performance and caching strategies, working with PostgreSQL, Redis, and related technologies.
• Support production deployments, including automation and infrastructure management using Docker and container orchestration tools like Kubernetes or Docker Swarm.
• Contribute to the development of fault-tolerant, distributed systems that can handle high concurrency and ensure data consistency.
• Work on transaction routing logic, webhook infrastructure, and related backend services to support real-time payment processing.
• Ensure compliance with security standards such as HMAC signatures, replay attack protections, and PCI DSS requirements.
• Maintain a focus on software quality through testing, structured logging, metrics collection, distributed tracing, and observability practices.
• Engage in continuous learning and development, leveraging AI-assisted tools like Cursor, Claude Code, and GitHub Copilot to enhance productivity and code quality.
• Support the team in troubleshooting production issues, identifying bottlenecks, and implementing scalable solutions.
• Contribute to documentation, technical specifications, and best practices for backend development within the organization.
• Stay updated with the latest trends in distributed systems, fintech security standards, and backend architecture to ensure the platform remains .

Requirements

• Proven expertise in .NET development, with deep knowledge of C# and experience working with .NET 8/9 frameworks.
• Extensive experience with ASP.NET Core for building web APIs and backend services.
• Strong understanding of asynchronous programming and concurrency models to build highly performant applications.
• Practical experience designing and implementing distributed systems, including event-driven architectures.
• Hands-on experience with Apache Kafka, including working with consumer groups, at-least-once delivery, manual offset commits, and idempotent consumers.
• Solid knowledge of database management, particularly with PostgreSQL, including SQL performance optimization and Dapper ORM.
• Experience working with Redis or similar caching solutions, including strategies such as Sentinel or Redis Cluster.
• Familiarity with containerization and orchestration tools like Docker and Kubernetes or Docker Swarm for production deployments.
• Understanding of security practices relevant to fintech, including HMAC signatures, replay attack mitigation, and PCI DSS compliance.
• Experience working in high-load, high-availability environments with a focus on reliability and fault tolerance.
• Knowledge of microservices architecture, message queues, and event-driven systems.
• Ability to work collaboratively with cross-functional teams, including Python and TypeScript developers.
• Strong commitment to software quality, including unit testing, integration testing, structured logging, metrics, and distributed tracing.
• Good communication skills and the ability to participate in architectural discussions and technical decision-making.
• Willingness to learn and adapt, leveraging AI-assisted development tools to improve productivity and code quality.

Nice to have

• Experience with Lua or LuaJIT scripting language for extending backend functionalities.
• Familiarity with OpenAPI-first development practices and tools like openapi-generator for API design and documentation.
• Knowledge of Python or TypeScript programming languages to facilitate collaboration with the Connector team.
• Experience with Git submodules for managing complex repositories and dependencies.
• Understanding of dynamic configuration management through event buses or similar mechanisms.
• Exposure to payment platform-specific workflows such as PayIn / PayOut flows, webhooks, callbacks, and payment routing strategies.
• Knowledge of cascade retry mechanisms, HMAC signatures, replay attack protections, and compliance standards like PCI DSS.

Skills & tools

• .NET 9 framework and ASP.NET Core for backend development.
• Kafka for event-driven messaging and distributed system communication.
• PostgreSQL for database management, with proficiency in SQL performance tuning.
• Redis for caching, with experience in Sentinel or Redis Cluster configurations.
• Dapper ORM for database interactions.
• Docker for containerization, with familiarity in deploying and managing containers.
• Kubernetes or Docker Swarm for container orchestration in production environments.
• Event-driven architecture principles and microservices design patterns.
• OpenAPI specifications and openapi-generator tools for API development.
• AI-assisted development tools such as Cursor, Claude Code, and GitHub Copilot to streamline coding workflows.

Practical notes

• This is an on-site position based in Europe, requiring presence at the office location.
• The role involves working on a modern, high-performance backend infrastructure for a fintech payment platform.
• The company emphasizes building reliable, scalable, and fault-tolerant systems, with a focus on security and compliance standards.
• The environment encourages continuous improvement, technical excellence, and ownership of the codebase.
• The team values clean architecture and best practices, with a strong focus on testing, observability, and system monitoring.
• AI tools are integrated into the development process, supporting engineers in writing high-quality code efficiently.
• The position offers an opportunity to work on mission-critical financial systems, impacting real-world transactions daily.
• The company promotes a collaborative culture where sharing knowledge and technical growth are encouraged.
• Candidates should be prepared to engage in architectural discussions, code reviews, and troubleshooting in a high-load production environment.