Full Stack Engineer (Kotlin/React)

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, describing risks to take and how to price them. These decisions shape real‑world outcomes: rockets launching into space, autonomous vehicles reaching the market, communities recovering after major storms. Until now, insurance has been making billion‑dollar decisions using outdated tools. We’re changing that by bringing together data, AI, and human expertise to give insurers the fastest path from submission to decision – helping them move faster, act smarter, and take 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.

About The Core Services Team

The Core Services team accelerates product development across hx by building foundational capabilities that every product team depends on. Our work sits at the intersection of platform engineering and product enablement, ensuring teams can move faster while maintaining high standards of security, scalability, and customer experience. We build and operate reusable platform services such as authorization, webhooks, notifications, API documentation, and API proxy infrastructure. These services form the backbone of the hx platform, enabling teams to focus on solving complex insurance problems while relying on robust shared systems for identity, access, and integration.

Software Engineer – Core Services

As a Software Engineer, you will help design and deliver the next generation of platform capabilities at hx, including building a scalable permissions and authorization service, defining how product teams integrate with it, and ensuring that the systems we build enable both internal teams and customers to move faster with confidence.

What you’ll be doing:

• Design and deliver a scalable authorization service that enables granular permissions across the hx platform.
• Define and validate a granular permissions model in collaboration with product and engineering teams, ensuring it supports teams, roles, risk, privacy, and model access across the platform.
• Build reusable platform services and SDKs that allow downstream teams to adopt core capabilities quickly.
• Develop infrastructure and APIs for platform capabilities such as authorization, webhooks, notifications, and API proxy services, ensuring they are secure, resilient, and easy to integrate.
• Partner closely with application teams to support adoption of the new permissions service, delivering an MVP that integrates with at least one production application.
• Contribute to engineering culture through strong operational discipline, clear documentation, and collaboration that raises the standard of platform engineering at hx.

What you’ll need to have done:

• Built and delivered backend or infrastructure services that enabled multiple teams to ship faster through reusable platform capabilities.
• Designed and implemented APIs or platform services that achieved high reliability, scalability, and maintainability in production environments.
• Delivered systems using Rust or Kotlin (or a JVM language) and demonstrated the ability to learn and apply new technologies when required, such as frontend exposure with React/Typescript.
• Implemented infrastructure using Terraform or other infrastructure‑as‑code tooling to support scalable cloud deployments.
• Delivered systems on cloud platforms such as AWS, ensuring operational robustness, observability, and long‑term maintainability.
• Collaborated with cross‑functional teams to design solutions, write clear documentation, and drive successful adoption of shared platform services.

You’re unlikely to thrive here if:

• You prefer highly defined problems and predictable delivery environments rather than working through ambiguity and shaping new platform capabilities.
• You focus only on your own component rather than taking responsibility for the wider outcome and adoption of the systems you build.
• You are uncomfortable collaborating closely with other teams or incorporating feedback into technical and product decisions.
• If reading our Culture Document leaves you feeling neutral rather than energized, hx may not be the place where you’ll do your best work.

Compensation

At hx, we’re committed to salary transparency. You’ll have clarity on pay early in the process, and we’re working toward publishing salary information for all roles globally. Equity is offered across all roles.

Benefits:

• £5,000 training and conference budget
• 25 days of holiday plus 8 bank holidays (33 days total)
• Company pension scheme via Penfold
• Mental health support and therapy via Spectrum.life
• Individual wellbeing allowance via Juno
• Private healthcare insurance through AXA
• Income protection and life insurance
• Cycle to Work Scheme

Additional perks:

• Top‑spec equipment (laptop, screens, adjustable desks, etc.)
• Regular remote and in‑person hackathons, lunch and learns, socials, and game nights
• Team breakfasts and lunches, snacks, drinks fridge, and a fun office at The Ministry
• Exceptional opportunities for personal development and growth as we build something remarkable together

Our commitment to Diversity

We recognise there's always more to do, and we take responsibility for shaping a workplace that is not only diverse but genuinely inclusive. If you’re energized by complexity and motivated to grow, we encourage you to apply and join our global team.

Note on background checks

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