Agentic .NET Backend Developer

B3 Consulting Poland; Kraków; On-site; PLN 220,000 - 260,000; Full time

Benefits offered by this job

Health benefits

Sports benefits

Speed Coaching

Team events and competitions

Job summary

B3 Consulting Poland is hiring a senior .NET Backend Developer to drive AI-assisted data platform features, focusing on autonomous AI agent workflows and MCP-based integrations.

You will author precise prompts and specs, build agent execution systems, and ensure code quality through automated evaluation suites and security reviews. Fluency in English and ability to work in Poland are required.

Qualifications

• Senior Backend foundation in .NET/C# and PostgreSQL, with a shift toward AI-assisted development.
• Practical experience with Model Context Protocol (MCP) implementations and integrations.
• Hands-on experience orchestrating AI developer tools, custom prompts, and repository contexts.
• Ability to translate complex business needs into precise spec prompts and testing criteria.
• Strong architectural judgment to evaluate code quality, query execution plans, and system design.
• Fluency in written English.
• You need to live in Poland and/or be eligible to work here.

Responsibilities

• Drive core data platform features by steering autonomous AI agent workflows (such as Claude Code) rather than writing code manually.
• Author clear, machine-executable specifications and prompts that serve as the source of truth for AI execution.
• Build and refine agent execution systems by integrating deterministic tooling, sandboxes, and Model Context Protocol (MCP) servers.
• Design automated evaluation suites, synthetic test environments, and quality gates to validate AI-generated code.
• Audit generated code for performance, security, memory efficiency, and multi-tenant isolation.

Skills

Backend development

.NET/C#

PostgreSQL

AI-assisted development

Model Context Protocol

Prompts & specs writing

Architectural judgment

English proficiency

Tools

Kafka

Debezium

MassTransit

RabbitMQ

Azure

Docker

Kubernetes

Job description

We are part of an international organization listed on Nasdaq Stockholm, operating in 11 countries. In Poland, we work with full autonomy. We independently choose our technologies, processes, and ways of working while maintaining the highest professional standards.

We deliver a wide range of IT projects in Poland and internationally, across multiple domains and technologies. This allows our consultants to develop their competencies and gain experience aligned with their professional ambitions.

Our collaboration is built around the CARE philosophy. For us, it means responsible project matching, transparent cooperation, and a long-term approach to professional growth.

Join us as Agentic .NET Backend Developer Grow in an environment that cares about your development as much as you do.

Your responsibilities

• Drive core data platform features by steering autonomous AI agent workflows (such as Claude Code) rather than writing code manually.
• Author clear, machine-executable specifications and prompts that serve as the source of truth for AI execution.
• Build and refine agent execution systems by integrating deterministic tooling, sandboxes, and Model Context Protocol (MCP) servers.
• Design automated evaluation suites, synthetic test environments, and quality gates to validate AI-generated code.
• Audit generated code for performance, security, memory efficiency, and multi-tenant isolation.

Requirements

• Senior Backend foundation in .NET/C# and PostgreSQL, with a shift toward AI-assisted development.
• Practical experience with Model Context Protocol (MCP) implementations and integrations.
• Hands-on experience orchestrating AI developer tools, custom prompts, and repository contexts.
• Ability to translate complex business needs into precise spec prompts and testing criteria.
• Strong architectural judgment to evaluate code quality, query execution plans, and system design.
• Fluency in written English.
• You need to live in Poland and/or be eligible to work here.

Nice to Have

• Multi-tenant SaaS architecture experience.
• Event-driven messaging (Kafka, Debezium, MassTransit, RabbitMQ).
• Cloud and container technologies (Azure, Docker, Kubernetes).

What we offer

• Work in a Scandinavian culture built on logic and dialogue.
• Health and sports benefits tailored to your needs.
• Speed Coaching – short sessions that provide new perspectives and solutions.
• Sports training, an internal team, and opportunities to take part in competitions.
• Team events and development-focused meetups.