Staff Engineer (Global Billing, Payments & API)

About the Position

Staff Engineer (Global Billing, Payments & API)

Join Kaluza as a Staff Engineer (Global Billing, Payments & API) to shape the future of energy intelligence and billing systems.

Responsibilities

Kaluza runs the billing and payments engine behind some of the world's biggest energy retailers. This role builds and evolves the platform other engineering teams build on top of: the shared APIs, integration patterns, and technical standards that let billing and payments capability get built once and reused everywhere, instead of rebuilt separately for every new market or client relationship.

Responsibilities include:

• Owning system design and architecture for the API Platform and Standards squad, not just a single service.
• Creating and challenging product and engineering proposals, backing design trade-offs with data.
• Diagnosing and resolving complex technical and product issues, including in areas outside your immediate domain.
• Establishing architectural patterns and technical standards that other teams build on top of.
• Taking ambiguous, loosely-defined technical requirements and turning them into a concrete plan others can execute against.
• Influencing engineering leadership, product, and adjacent squads to bring clarity and alignment on technical direction.
• Mentoring and upskilling engineers beyond your immediate team, contributing to a wider learning culture.

Requirements

• Deep technical expertise applied to system design and architecture ownership across a squad, not just a single team or service.
• Ability to create and challenge product and engineering proposals and make design trade-offs, backed by data.
• Track record diagnosing and resolving complex technical and product issues, including in domains you aren't already close to.
• Skilled at establishing and driving adoption of architectural patterns and technical standards that other teams build on top of.
• Comfortable taking ambiguous, loosely-defined technical requirements and turning them into a concrete plan others can execute against.
• Accomplished at influencing both upwards and outwards, bringing clarity and alignment to engineering leadership, product, and adjacent squads on technical direction.
• Track record mentoring and upskilling other engineers, and fostering a learning culture beyond your own immediate team.
• Comfortable operating in a high-integrity data domain (billing or payments), where reliability, security, and auditability come before speed.
• Demonstrable customer obsession and a working-backwards practice: start from the problem other engineering teams or end customers have, and design the simplest platform capability that solves it.
• Demonstrable record of applying AI/LLMs to deliver customer impact, not just adopting AI tooling internally.

Nice to Have

• Direct experience with API gateway, versioning, or developer-experience standards work at scale.
• Direct experience in billing, payments, or financial-services domains.
• Experience operating a "global core, configurable edge" or multi-market platform model (one engine, configuration at the edge, no client-specific forks of core logic).

We Offer

• Location: London / Bristol / Edinburgh (Hybrid Office - 3+ days per week)
• Salary: £97,000 - £122,000
• Team: Global Billing, Payments & API
• Level: TL2

Perks

• Pension Scheme
• Discretionary Bonus Scheme
• Private Medical Insurance + Virtual GP
• Life Assurance
• Access to Furthr - a Climate Action app
• Free Mortgage Advice and Eye Tests
• Perks at Work - access to thousands of retail discounts
• 5% Flex Fund - to spend on the benefits you want most
• 26 days holiday
• Progressive Leave Policy - With no qualifying service periods, including 26 weeks full pay if you have a new addition to your family
• Personal Learning Budget - Upskill, learn and grow!
• Home Office Budget

About the Company

Kaluza is the Energy Intelligence Platform, turning energy complexity into seamless coordination. We help energy companies overcome today’s challenges while accelerating the shift to a clean, electrified future.

Our platform orchestrates millions of real-time decisions across homes, devices, markets and grids. By combining predictive algorithms with human-centred design, Kaluza makes clean energy dependable, affordable and adaptive to everyday life.

With teams across Europe, North America, Asia and Australia, and a joint venture with Mitsubishi Corporation in Japan, we power leading companies including OVO, AGL and ENGIE, as well as innovators like Volvo and Volkswagen.

Kaluza Values

Here at Kaluza we have five core values that guide us as a business: Play to win, Solve the real problem, Build trust every day, Own the outcome, Go further together.

Ready to Transform Your Product Offerings?

Contact us today to learn more about working in Kaluza on our careers page and LinkedIn.