Senior .NET Engineer (Data Platform & AI Agents)

Key areas of the role

• Designing and developing data platform services in a multi-tenant SaaS architecture (data ingestion, schema management, snapshots, calculated fields, exports) using .NET, Entity Framework/Dapper and PostgreSQL
• Building tools that dynamically generate performant queries, tailored to each customer's unique data model - with a focus on performance and cost optimization (bulk ingestion, streaming, complex SQL queries)
• Developing agentic tooling supporting the team's work (custom skills and sub-agents, MCP tools exposing internal APIs) and collaborating with Data Platform, Analytics, Support and Product teams to ensure the quality of AI-generated code

What you need to join us

Must have

• Senior-level, 5+ year experience building production, performant and scalable backend services in .NET/C# (preferably in a multi-tenant SaaS environments)
• Strong SQL and PostgreSQL skills (schema design, query optimization)
• Performance/memory awareness (streaming vs. buffering, profiling, load testing), along with understanding of .NET architecture
• Daily experience working with AI/agents (e.g. Claude Code) - turning requirements into agent-executable specifications and critically reviewing outcomes (hallucinations, architectural drift, security issues)
• Testing and quality discipline (unit/integration tests) and excellent written communication (architecture documentation, specifications, PR descriptions)
• Fluent English (C1)
• Eligibility to work in Poland (citizenship, residence card, visa, etc.)

Nice to have

• Microsoft Fabric or Spark
• MCP servers or exposing internal APIs as agent-callable tools
• LLM evaluation (eval suites, behavioral test design, benchmarking agent workflows)