Senior .NET Developer

Role Summary

B3 Consulting's vision is to create a world of technology in which people come first. We come from Sweden, and our mission is to take care of how we live and work .

Our "Care" philosophy results in technology meeting care, which allows us to build long-term relationships while creating innovative solutions.

At B3, we unleash the potential of companies through IT outsourcing in a unique, Scandinavian model. We are one of the fastest growing companies in Poland, awarded the title of "Business Gazelle" in 2023 💪

If, like us, you value

💥 Energy

💡 Logic

Responsibilities

• Design, build, and operate backend microservices using .NET (C#, Core)
• Build and evolve client-facing APIs with strong focus on: versioning; backward compatibility; long-term maintainability
• Work with event-driven systems ( Google Pub/Sub, Kafka )
• Improve platform stability, performance, and scalability
• Participate in production support and incident resolution
• Collaborate closely with platform, product, embedded, and mobile teams
• Take end-to-end ownership from design to production

On board with B3 you will receive

• Health and sports benefits tailored to your needs
• Free running and swimming training, internal triathlon team, joint competitions (Warsaw)
• Tailor-made development activities to deepen expert knowledge
• Cyclical initiatives allowing development in IT fields other than the current one
• We are waiting for you! 🦓

Requirements

This is great - we fit together perfectly!

The project comes from Natue/Forestry industry and concerns building a large-scale, real-time platform powering mobile apps, IoT devices, and backend services for hundreds of thousands of users — even under extreme peak loads. We’re looking for engineers passionate about building robust, long-lasting systems — not just shipping features.

Your skills

·Strong experience with .NET backend development (C#, Core)

• Solid understanding of microservice architectures
• Experience building production-grade APIs
• Experience with messaging systems (Google Pub/Sub and/or Kafka)
• Proven experience running and maintaining production systems
• Strong testing and debugging skills (unit, integration, performance)
• Comfortable with Git and modern development workflows (code reviews, CI/CD)
• Clear communication and documentation skills
• Strong ownership mindset — you care about what happens after deployment
• Willingness to use AI tools responsibly to improve development productivity
• Fluent in English communication