Senior AI Builder for Agent‑First B2B SaaS

Everfield; Warszawa; On-site; PLN 200,000 - 320,000; Full time

Job summary

Everfield, a portfolio of European B2B SaaS businesses, is hiring an AI Builder to join its product team in Warsaw. You'll prototype with agentic coding tools, ship features end-to-end inside BU codebases, and work closely with BU engineers and the Product Lead.

You'll operate across stacks, translate ideas into production, and help scale AI capabilities across multiple BUs while maintaining production-ready quality and clear documentation.

Qualifications

• Senior engineer with shipped software and user impact.
• Founding or near-founding experience in a tech startup.
• Experience using AI-native tooling and agentic coding workflows.
• Ability to work across stacks and multiple languages.
• Comfort working with legacy codebases and BU environments.
• Direct exposure to customers with ability to iterate based on usage.
• 3–8 years of engineering, founding, or hybrid roles.
• Ability to jump between BUs, codes, and customer segments.

Responsibilities

• Build agent-first products end to end inside BU codebases.
• Drop into BU codebases and produce working software fast.
• Run agentic coding with Claude Code, Codex, SpecKit.
• Prototype directly with BU customers and iterate based on actual usage.
• Work side by side with BU engineering teams on their codebase for maintainability.
• Translate validated ideas into shipped products in weeks.
• Hand off production-ready code and documentation to BU teams.
• Spot the next build opportunity while delivering the current one.
• Help codify repeatable build playbooks to scale across BUs.

Skills

Senior engineer

Founder or near-founder experience

AI-native ways of working

Polyglot pragmatism

Comfort with legacy code

Direct customer exposure

3–8 years experience

Ambiguity tolerance

Education

Engineering degree

Tools

Claude Code

Codex

SpecKit

Job description

Everfield, a portfolio of European B2B SaaS businesses, is hiring an AI Builder to join its product team in Warsaw. You'll prototype with agentic coding tools, ship features end-to-end inside BU codebases, and work closely with BU engineers and the Product Lead.

You'll operate across stacks, translate ideas into production, and help scale AI capabilities across multiple BUs while maintaining production-ready quality and clear documentation.