Senior Software Engineer (JVM/Kotlin) - Warsaw

About hyperexponential (hx)

At hyperexponential, we're building the AI-powered platform that enables the world's most critical decisions in a $7 trillion industry, which risks to take, and how to price them. These are the decisions that shape real-world outcomes: whether rockets successfully launch into space, autonomous vehicles make it to market, or communities recover after major storms.

Until now, insurance has been making billion-dollar decisions using outdated tools. We're changing that. Our platform brings together data, AI, and human expertise to give insurers the fastest path from submission to decision - helping them move faster, act smarter, and take on more risk with confidence.

Backed by a16z, Highland Europe, and Battery Ventures, we're scaling globally - already trusted by nearly 50 of the world's largest insurers, with zero churn and billions in premiums flowing through hx.

What began as a single product in one market has rapidly evolved into a multi-product, multi-territory platform powering every stage of pricing and underwriting. AI is at the core of what we do - from building the world's first domain-specific AI peer programmer for insurance (think GitHub Copilot with a PhD in actuarial science) to shaping agentic workflows that reinvent how this industry operates.

What makes hx different is the people who build it. Here, impact isn't tied to title or tenure; it's defined by the challenges you take on and the discipline you bring. Surrounded by peers who stretch you, you'll do the best, hardest work of your life in a company engineered to endure.

If that sounds like you, join us in building what comes next.

About the Policies team

Engineering at hx drives every breakthrough that transforms how insurers make billion-dollar decisions. At the core of our product sits the Policies team - the engineers who build and maintain the critical systems that track models, policies, and the complex business logic that powers hx Renew. This team manages some of our most business-critical data and workflows, ensuring that billions in premiums flow through robust, reliable systems.

As a Senior Backend Engineer in the Policies team, you'll lead the architectural transformation of our core domain while delivering the new features that expand our product capabilities. You'll be architecting the evolution from monolith to modular systems, implementing Domain-Driven Design and hexagonal architecture patterns that will shape how we scale for the next phase of growth.

This role combines deep technical leadership with direct product impact - you'll influence architectural decisions that affect the entire platform while building the features that serve nearly 50 of the world's largest insurers. If you want to shape critical systems architecture while seeing your work power billion-dollar insurance decisions, this is where you'll lead that transformation.

What you'll be doing

• Lead architectural modernisation of core business systems, driving the transition from monolith to modular architecture using Domain-Driven Design principles that enable faster development and better system maintainability.

• Design and deliver complex business logic in Kotlin, Spring, and Hibernate, building robust systems that handle intricate insurance domain models and maintain data integrity for billions in premiums.

• Shape technical strategy and standards across the team and broader engineering organisation, driving decisions around system design, code quality, and architectural patterns that other teams will follow.

• Collaborate with product stakeholders to translate complex business requirements into elegant technical solutions, working directly with product managers, designers, and sometimes customers to ensure we're solving the right problems.

• Mentor and influence engineering culture by establishing coding standards, leading technical discussions, and helping other engineers grow their architectural thinking and technical skills.

• Drive operational excellence through participation in on-call rotations and building systems that maintain high availability for our mission-critical platform used by enterprise customers worldwide.

What you'll need to have done

• Architected and delivered complex backend systems with proven experience leading technical initiatives in Kotlin or other JVM languages, ideally with hands-on knowledge of Spring, Hibernate, or similar enterprise frameworks.

  • You will be upskilled in Kotlin if you didn’t already use it!

• Led architectural transformation projects with demonstrable success modernising legacy systems, implementing Domain-Driven Design, or breaking down monoliths into maintainable, modular architectures.

• Influenced technical strategy across teams by driving architecture decisions, establishing coding standards, and mentoring other engineers in best practices that improved system quality and development velocity.

• Built business-critical systems that handled complex domain logic and data integrity requirements, ideally in industries like finance, insurance, or other domains where system reliability directly impacts business outcomes.

• Collaborated effectively with product teams to deliver features that customers actually use, with evidence of translating business requirements into technical solutions that drive measurable impact.

• Demonstrated senior-level ownership by taking responsibility for system reliability, participating in on-call rotations, and building the operational practices that keep production systems running smoothly.

You're unlikely to thrive here if

• You prefer working within established architectural patterns rather than leading the design and implementation of new system architectures in a rapidly evolving environment.

• You're more comfortable focusing on individual feature delivery than taking broader responsibility for system architecture, technical standards, and mentoring other engineers.

• You're not excited by the challenge of modernising complex business systems while maintaining reliability for enterprise customers who depend on continuous uptime.

• If reading our Culture Document leaves you feeling neutral rather than energised, hx may not be the place where you'll do your best work. We're building something that asks for commitment and conviction, and we want you to feel excited by the opportunity to grow with us.

Compensation

At hx, we're committed to salary transparency. You'll always have clarity on pay early in the process - our Talent Partner will share details with you during initial conversations - and we're working towards publishing salary information for all roles globally.

Because we're building at the intersection of technology/SaaS and insurance, our roles don't always map neatly onto traditional benchmarks. Our approach is to design compensation that's competitive in the market, fair across teams, and aligned with the impact our people make.

Equity: We offer equity across all roles at hx, making it a significant component of total compensation. Your talent partner will be able to share more details about this.

Benefits

Depending on how you choose to join hx (B2B or UoP), your benefits can look like:

B2B

• Share Options at a highly successful Series B company

• 25 days of non-working + 14 Polish bank holidays

• £5,000 budget for Learning & Development

• Mental Health Support and Therapy via Spectrum Life

• Optional for you: access to Healthcare package provided by Luxmed + Multisport (fully funded by yourself as B2B Contractor)

• Top-spec laptop (MacOS or Windows)

Contract of employment (UoP)

• Share Options at a highly successful Series B company

• £5,000 budget for learning & development

• 26 days of holiday + 14 Polish bank holidays

• Company pension

• 10 days company sick pay at 100% salary, thereafter in line with labour law

• Mental health support and therapy via Spectrum Life

• Monthly wellbeing allowance via Juno

• Healthcare package provided by Luxmed

• Multisport card at Classic level

• Top-spec work equipment (MacOS / Windows + additional monitors, mechanical keyboards etc)

Interview process

1. Initial call with our Talent team to kick things off (30 minutes)

2. Manager Interview (60 minutes)

3. Technical Assessment (120 minutes)

4. Values Interview (60 minutes)

5. We offer!

Our commitment to Diversity

hxer's are at the centre of everything we build. We know that progress depends on diverse perspectives, and we are committed to creating an environment where everyone can thrive, grow, and make an impact. We recognise there is always more to do, and we take responsibility for shaping a workplace that is not only diverse but genuinely inclusive.

Diversity is not just the right thing to do, it is key to solving the complex challenges we choose to take on. By welcoming people from all backgrounds and experiences, we strengthen our ability to question assumptions, push boundaries, and design solutions that endure. If you're energised by complexity and motivated to grow, we encourage you to apply and join our global team.

Next steps:

If this opportunity resonates with you, we encourage you to apply or share it with your connections! Our dedicated talent team reviews all applications, and we promise to provide feedback regardless of the outcome.

For more information about applying and to view other opportunities, you can visit our careers page.

Please note that background checks will be conducted as part of the hiring process to ensure compliance with our governance policies. We handle all background checks sensitively and in full compliance with relevant regulations. All applicant data will be processed in accordance with data protection regulations and our privacy policy.