Senior .NET Engineer (Payment Platform)
- Role
- Backend
- Experience
- Senior
- Employment
- Full-time
Open to Anywhere in EU + UA. Set where you work from to check your eligibility.
No BS summary
Senior backend .NET engineer for a remote full-time payment platform role hiring in the EU and Ukraine. Needs strong C#/.NET 8/9, ASP.NET Core, Kafka, PostgreSQL, Redis, Docker, distributed systems, and fintech/payment experience.
Core skills
Required skills
Optional skills
Fintech & AI-assisted | Remote | Full-time
About the company
Our client is building a high-load payment platform that processes thousands of transactions around the clock.
Their engineering challenges are far beyond typical CRUD applications. They build distributed systems where reliability, scalability, performance, and fault tolerance are critical. The platform is designed around an event-driven architecture using .NET 9, Kafka, PostgreSQL, Redis, and Docker.
If you're excited by solving complex backend problems and building systems that must never fail, we'd love to talk.
What you'll do
- Build and evolve the core of our payment platform.
- Design new services and payment provider integrations from architecture to production.
- Improve transaction processing, routing, and webhook infrastructure.
- Participate in architectural decisions and technical discussions.
- Review code, share knowledge, and help maintain a high engineering standard.
- Work closely with our Connector team (Python / TypeScript).
We're looking for someone who has
- Strong .NET expertise
- Deep knowledge of C# and .NET 8/9.
- Solid experience with ASP.NET Core.
- Strong understanding of asynchronous programming.
- Experience building highly concurrent applications.
- Production experience with Minimal API, Hosted Services and Dependency Injection.
- Experience building distributed systems
You understand concepts like:
- event-driven architecture;
- idempotency;
- Inbox / Outbox pattern;
- reliable message delivery;
- microservices;
- distributed transactions.
- Apache Kafka
Hands-on production experience with:
- consumer groups;
- at-least-once delivery;
- manual offset commits;
- idempotent consumers.
- Databases & Caching
- PostgreSQL;
- Dapper;
- SQL performance optimization;
- Redis / Valkey;
- caching strategies;
- Sentinel or Redis Cluster.
- Infrastructure
- Docker;
- container orchestration (Docker Swarm or Kubernetes);
- production deployments.
- FinTech experience
Ideally you've worked with:
- payment platforms;
- PayIn / PayOut flows;
- webhooks;
- callbacks;
- payment routing;
- cascade retry;
- HMAC signatures;
- replay attack protection;
- PCI DSS requirements.
- Engineering mindset.
You care about software quality and production reliability.
You regularly work with:
- unit and integration testing;
- structured logging;
- metrics;
- distributed tracing;
- observability.
- AI-assisted development
- AI is part of our engineering workflow.
We expect engineers to confidently use tools like Cursor, Claude Code, GitHub Copilot or similar while maintaining full ownership of the produced code.
Nice to have
- Lua / LuaJIT
- OpenAPI-first development
- openapi-generator
- Python or TypeScript
- Git Submodules
- Dynamic configuration through event buses
Tech Stack:
.NET 9 • ASP.NET Core • Kafka • PostgreSQL • Redis • Dapper • Docker • Event-driven Architecture • Microservices • OpenAPI • AI-assisted Development
Why join us?
- You'll work on a product where engineering decisions truly matter.
- Instead of maintaining legacy enterprise software, you'll help build the core infrastructure of a modern payment platform used in production every day.
- You'll join a team that values clean architecture, ownership, technical excellence, and continuous improvement.
- If solving challenging distributed systems problems motivates you, you'll feel at home here.
What you'll do
- Build and evolve the core of the payment platform.
- Design new services and payment provider integrations from architecture to production.
- Improve transaction processing, routing, and webhook infrastructure.
- Participate in architectural decisions and technical discussions.
- Review code, share knowledge, and help maintain a high engineering standard.
- Work closely with the Connector team using Python and TypeScript.
What they require
- Strong .NET expertise.
- Deep knowledge of C# and .NET 8/9.
- Solid experience with ASP.NET Core.
- Strong understanding of asynchronous programming.
- Experience building highly concurrent applications.
- Production experience with Minimal API, Hosted Services, and Dependency Injection.
- Experience building distributed systems.
- Understanding of event-driven architecture.
- Understanding of idempotency.
- Understanding of Inbox / Outbox pattern.
- Understanding of reliable message delivery.
- Understanding of microservices.
- Understanding of distributed transactions.
- Hands-on production experience with Apache Kafka consumer groups.
- Hands-on production experience with at-least-once delivery.
- Hands-on production experience with manual offset commits.
- Hands-on production experience with idempotent consumers.
- Experience with databases and caching.
- Experience with PostgreSQL.
- Experience with Dapper.
- Experience with SQL performance optimization.
- Experience with Redis / Valkey.
- Experience with caching strategies.
- Experience with Sentinel or Redis Cluster.
- Experience with infrastructure.
- Experience with Docker.
- Experience with container orchestration using Docker Swarm or Kubernetes.
- Experience with production deployments.
- FinTech experience.
- Experience with payment platforms.
- Experience with PayIn / PayOut flows.
- Experience with webhooks.
- Experience with callbacks.
- Experience with payment routing.
- Experience with cascade retry.
- Experience with HMAC signatures.
- Experience with replay attack protection.
- Experience with PCI DSS requirements.
- Engineering mindset.
- Care about software quality and production reliability.
- Regularly work with unit and integration testing.
- Regularly work with structured logging.
- Regularly work with metrics.
- Regularly work with distributed tracing.
- Regularly work with observability.
- Confidently use AI-assisted development tools like Cursor, Claude Code, GitHub Copilot, or similar while maintaining full ownership of the produced code.
Benefits
- Work on a product where engineering decisions truly matter.
- Help build the core infrastructure of a modern payment platform used in production every day instead of maintaining legacy enterprise software.
- Join a team that values clean architecture, ownership, technical excellence, and continuous improvement.
- Work on challenging distributed systems problems.
OnHires' client is an international digital services company that provides marketing, technology, analytics, and operational support to fast-growing global brands, supporting a rapidly growing iGaming project focused on Latin American markets.