Senior Full-Stack Engineer (Kotlin & TS)

O projekcie: Vecten | Client: US-based, retirement plan administration | Remote (Poland-based) | Contract / B2B We are an AI-native data and technology partner for private capital and healthcare. Founded in 2010 and headquartered in Warsaw, we work with leading PE firms, VC funds, and healthcare organizations to build proprietary data infrastructure, deploy AI solutions, and drive AI-native transformation. Our clients manage a cumulative $210B+ in assets. Our average engagement runs five years. Our NPS sits above 80. We don't need to claim credibility — we can show it. We've also done to ourselves what we now do for clients. We've restructured our own company around AI — tools, policies, roles, delivery models. This isn't a pitch. It's a playbook we've already run, and we're hiring the engineers who will run it for others. - Financial Platform Rebuild - You'd be joining a small, senior team rebuilding a 401(k) plan administration platform from the ground up. The existing system was built and operated by a third party; the client is taking ownership and rebuilding it greenfield with a strong AI-native foundation. This is not a ticket-taking role. You'll sit in product conversations with business users, push back on requirements, propose architectural directions, and own end-to-end delivery from infrastructure to UI. The client is US-based with engineers on both coasts. Working hours need meaningful overlap with US East Coast (afternoon CET works well). What you'd be doing - Designing and building the core platform: event processing for money math, plan configuration, eligibility rules, and the supporting services around them.- Owning vertical slices end-to-end – AWS infrastructure, Kotlin backend, TypeScript frontend.- Acting as a thought partner on architecture decisions still being made (IaC choice, service boundaries, data model).- Interviewing internal subject-matter experts to translate domain knowledge into working software.- Setting the bar for AI-native engineering practices – how the team uses Claude Code, Cursor, agents, and what good looks like. Logistics - Engagement model: Contract via Vecten (B2B), initial 3–6 month commitment with strong likelihood of extension.- Hardware: Vecten provides a managed, secured environment.- Interview process: Vecten internal screen → tech screen with the client's tech lead → live coding session (likely screen-share, AI-assisted format) → culture call.- Start: Ideally within 2–4 weeks. Strongly preferred - AI-native fluency – you actively use Claude Code, Cursor, or equivalent agents in your daily workflow. You can talk specifically about what you delegate, what you don't, and why.- AWS in production – not just "deployed something once". Deep familiarity with VPCs, IAM, RDS, Lambda/ECS trade-offs on real workloads.- IaC experience – Pulumi, Terraform, or CDK.- Background in regulated or transactional domains – fintech, payments, healthcare, insurance, ERP, billing systems. Anything where audit trails, eligibility rules, and money math matter.- Comfort working in greenfield ambiguity – you've been the second or third engineer on a platform before and know how to make progress when half the decisions aren't made yet. What we're not asking for - A specific number of years on Kotlin, AWS, or any one tool. We care about depth of judgment, not box-ticking.- Front-end specialisation. You don't need to debate React Server Components – you need to ship working UI.- Big-bank or HFT pedigree. This is retirement plan administration, not trading. Benefits - Unrestricted AI Stack & Premium Gear: Fully paid licenses for Cursor, Claude Pro, etc.- Work with a talented team redefining the global perception of Poland- Flexible working hours and remote work options- Comfortable office in central Warsaw with all essential tools- Multisport card & private medical care- A culture of feedback – evaluation meetings, mentoring, and career growth opportunities- Frontier Engineering Culture: Build alongside elite engineers who are shipping systems that drive real investment decisions. Backed by continuous growth and a strong knowledge-sharing culture (check our YouTube). Sounds like a perfect place for you? Don’t hesitate to click apply and submit your application today! Wymagania: Must-have - 7+ years of professional software engineering experience, with a meaningful track record of senior or staff-level work.- Strong backend engineering on the JVM – Kotlin, Java, or Scala in production. Kotlin experience preferred; if you have strong Java/Scala and have shipped Kotlin on a side project, that works.- Solid TypeScript on the frontend – React, Angular, or similar, enough to own UI slices without needing a dedicated frontend pair.- Solid cloud infrastructure fundamentals – you've reasoned about networking, IAM, compute, and managed services for real systems and can defend the trade-offs.- Architecture chops – you've designed non-trivial systems, can defend trade-offs, and are comfortable disagreeing when you think someone's wrong.- English fluency – you'll be talking to business users and engineers daily. Nice to have - Direct retirement / pensions / 401(k) experience – the unicorn profile. If you have it, lead with it.- DevOps depth – you've owned CI/CD pipelines, observability stacks, and on-call rotations.- Python data-stack background – likely to become relevant as analytics and reporting work comes online. Codzienne zadania: - Designing and building the core platform: event processing for money math, plan configuration, eligibility rules, and the supporting services around them. - Owning vertical slices end-to-end – AWS infrastructure, Kotlin backend, TypeScript frontend. - Acting as a thought partner on architecture decisions still being made (IaC choice, service boundaries, data model). - Interviewing internal subject-matter experts to translate domain knowledge into working software. - Setting the bar for AI-native engineering practices – how the team uses Claude Code, Cursor, agents, and what good looks like.