Full Stack Engineer (Kotlin/React) in London

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. Our platform brings together data, AI, and human expertise to give insurers the fastest path from submission to decision.

About the Core Services team

The Core Services team exists to accelerate product development across hx by building the foundational capabilities that every product team depends on. Our work sits at the intersection of platform engineering and product enablement, ensuring that teams can move faster while maintaining high standards of security, scalability, and customer experience.

As a Software Engineer in the Core Services team, you will help design and deliver the next generation of platform capabilities at hx. This includes building a scalable permissions and authorisation 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 authorisation service that enables granular permissions across the hx platform.
• Define and validate a granular permissions model in collaboration with product and engineering teams.
• Build reusable platform services and SDKs that allow downstream teams to adopt core capabilities quickly.
• Develop infrastructure and APIs for platform capabilities such as authorisation, webhooks, notifications, and API proxy services.
• Partner closely with application teams to support adoption of the new permissions service.
• Contribute to engineering culture through strong operational discipline, clear documentation, and collaboration.

What you’ll need to have done:

• Built and delivered backend or infrastructure services that enabled multiple teams to ship faster.
• Designed and implemented APIs or platform services that achieved high reliability, scalability, and maintainability.
• Delivered systems using Rust or Kotlin (or a JVM language) and demonstrated the ability to learn and apply new technologies.
• Implemented infrastructure using Terraform or other infrastructure-as-code tooling.
• Delivered systems on cloud platforms such as AWS.
• Collaborated with cross-functional teams to design solutions and drive successful adoption of shared platform services.

You’re unlikely to thrive here if:

• You prefer highly defined problems and predictable delivery environments.
• You focus only on your own component rather than taking responsibility for the wider outcome.
• You are uncomfortable collaborating closely with other teams.

Compensation:

At hx, we’re committed to salary transparency. We offer equity across all roles at hx, making it a significant component of total compensation.

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.
• Regular remote and in-person hackathons, lunch and learns, socials, and game nights.
• Exceptional opportunities for personal development and growth.

Interview Process:

• Initial call with Talent team (30 minutes).
• Manager Interview (60 minutes).
• Technical Assessment (120 minutes).
• Values Interview with Tech Leadership (60 minutes).
• Offer.

Our commitment to Diversity:

hxer's are at the centre of everything we build. We are committed to creating an environment where everyone can thrive, grow, and make an impact.

Next steps:

If this opportunity resonates with you, we encourage you to apply or share it with your connections!