Senior Model Developer 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 - 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 Until now, insurers have been making billion-dollar decisions using outdated tools.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 Model Development team

The hyperexponential Model Development team (MDT) is a unique blend of engineers, actuaries, mathematicians and data scientists. We don’t take on traditional “transformations” (we have brilliant partners for that) – we specialise in handling only the most difficult and interesting problems our customers face, where only a combination of technical depth, market expertise and hx Renew knowledge will do. The MDT are the experts' experts of hx Renew, knowing it top-to-bottom, inside-out – both breadth and depth. You’ll learn its limits and which can be pushed. You’ll uncover every trick in the book, the secret combinations, and the shortcuts. You’ll combine all of this with a growing knowledge of insurance technology to present 'the art of the possible' to our customers and help shape cutting-edge tech, while working alongside some of the brightest, most ambitious people in the tech and insurance industries.

What you’ll be doing

• Own end-to-end delivery of complex models on hx Renew, from scoping and technical design through build, testing, iteration, and customer delivery.
• Build and maintain production-grade Python models, setting a high bar for code quality, testing, and modelling best practices.
• Act as a technical authority on customer projects, working directly with actuarial teams and senior stakeholders to solve complex, ambiguous problems.
• Raise quality across the team through code review, pairing, mentoring, and contributions to shared guidance and standards.
• Support the development of other Model Developers, providing feedback and technical leadership in day-to-day delivery.
• Proactively identify opportunities to improve tooling, processes, and ways of working to increase delivery speed, predictability, and quality.

What you’ll need to have done

• Shipped and maintained production-grade Python code in complex, data-heavy environments.
• Delivered actuarial, pricing, or advanced analytical models in real-world settings (insurance or reinsurance experience is strongly preferred).
• Taken ownership of complex, ambiguous problems, creating structure and driving them through to high-quality outcomes.
• Worked directly with customers or senior non-technical stakeholders, translating requirements into robust technical solutions.
• Acted as a senior contributor within a team, influencing quality, standards, and ways of working beyond your own tasks.
• Operated effectively in a high-trust, high-accountability environment, demonstrating ownership, judgement, and continuous learning.

You’re unlikely to thrive here if

• You prefer following detailed instructions rather than experimenting and finding your own approach.
• You are uncomfortable working directly with non-technical stakeholders to understand their challenges.
• You avoid tackling ambiguous or open-ended problems where the solution isn’t obvious.
• 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

£5,000 training and conference budget for individual and group development. 25 days of holiday plus 8.