Senior Staff Engineer - Transaction Platform in London

Who We Are: We are rebuilding the energy transaction, making it transparent and fair. Our goal is to put power back where it belongs, in the hands of customers and to take on one of the most critical problems of our century, access to low cost electricity. We exist to fix a broken global energy market that’s long favoured legacy operators, intermediaries, and opaque pricing. Today’s electricity system was not designed for rapid decarbonisation, AI‑driven efficiency or fair access for the actual users – businesses and generators. We’ve built the first AI native transaction infrastructure to reinvent how electricity is bought, sold and priced. Our technology is designed to cut out the inefficient fees, automate complex market flows, and bring transparency and fairness to energy transactions at scale.

In late 2025, after extraordinary growth, we closed a $75 million Series B – led by Lightspeed Venture Partners with participation from Albion, Atomico, Allianz, Hitachi Ventures, Schroders Capital and others – positioning us for global expansion, deeper product innovation and category leadership. We’re scaling internationally and building toward a future where AI‑driven infrastructure is foundational to electricity markets worldwide. Since launch, our modern utility product, known as RED, has already facilitated thousands of business customers and billions in energy transaction value, proving that modern software and AI can transform an industry built on legacy systems. At tem, we’re not just building another energy company, we’re rearchitecting market infrastructure so that transparency, efficiency and sustainability become the default, not the exception.

The Role: Rosso is tem's core pricing infrastructure. It brings together forecasting, margin optimisation, and portfolio balancing to price energy tenders from first input through to signed contract – and keeps the portfolio healthy as we grow. It sits directly on the critical path for revenue. You’ll join a team with strong product vision and technical leadership and take on complex deliveries end‑to‑end – owning the architecture, writing the code, raising system quality, and preventing domain drift as the platform and organisation scale. You’ll work closely with our ML and Data Science teams and play a meaningful role in how pricing models are integrated into production. This role combines deep hands‑on engineering with strategic technical ownership. We’re looking for someone who drives to concrete solutions under ambiguity, uses the people around them as a resource, and takes accountability for outcomes – not just execution. If your instinct when given a hard problem is to get into it, commit to a direction, and deliver – this role is for you.

Responsibilities:

• Own and ship complex deliveries.
• Lead high‑impact improvements across Rosso's pricing and deal‑flow workflows – improving correctness, operability, and scalability as volume and complexity grow. You drive these from design through to production.
• Make architectural decisions that stick.
• Design and evolve a stateful, event‑driven system where domain logic is the primary source of complexity. Create clear domain boundaries and prevent the kind of drift that compounds over time.
• Partner with ML and Data Science.
• Work closely with our ML and Data Science teams on integrating forecasting, optimisation, and pricing models into Rosso's core workflows. You don’t need to be an ML practitioner – but you’ll be a genuine technical partner in how models land in production.
• Lead across teams.
• Drive cross‑functional initiatives spanning engineering, product, data, and commercial stakeholders. Align people around a technical direction and deliver.
• Raise the bar.
• Mentor Staff and Senior Engineers, strengthen observability and testing practices, and act as a trusted technical voice to engineering leadership.
• Plan for scale.
• Architect systems for high‑volume quoting activity and large customer counts – anticipating bottlenecks before they emerge.

Requirements:

Must‑Haves:

• You operate at Staff+ level with a track record of organisation‑wide impact.
• You’ve owned major technical initiatives at a high‑growth startup and can point to what changed because of it. Not just influence – shipped outcomes.
• You have deep application architecture experience in complex domains.
• You’ve designed and evolved stateful distributed systems – APIs, event‑driven architectures, data systems – where business logic is the hard part. You know what domain drift looks like and how to prevent it.
• You’re comfortable working in Python. Our codebase is Python. You don’t need to be a Python specialist, but you should have meaningful exposure to production Python systems and be confident contributing to and reviewing Python code from day one.
• You’re strong with AWS serverless architecture. Hands‑on experience with Lambda, API Gateway, DynamoDB, and event‑driven, asynchronous workflows – operated in production and learned from failure.
• You can drive to a concrete decision under ambiguity. You ask sharp questions to narrow the problem space, commit to a direction, and take responsibility for the outcome. You don’t narrate a methodology – you execute one.
• You connect technical decisions to business outcomes. Technical authority and business accountability aren’t in tension for you – they’re the same thing.
• You lead cross‑team work. You’ve run initiatives that span engineering, product, data, and commercial stakeholders – and you’ve delivered them, not just coordinated them.

Desirable:

• Hands‑on experience productionising ML models (forecasting, optimisation, pricing, or similar).
• Experience in real‑time pricing engines, energy markets, or financial infrastructure.
• Exposure to regulated industries (energy, fintech, govtech).
• Experience scaling systems from early PMF to multi‑product platforms.
• Experience improving engineering team topology or platform strategy.
• High‑performance/high‑scale environments (Kubernetes, Spark, or similar).

Benefits & Perks:

• Competitive salary – We review salaries twice a year using real‑time market data, with transparent, consistent pay for the same role and level.
• Stock Options – everyone on the team has ownership in our mission.
• 25 days holiday + public holidays – Swap public holidays for ones that matter most to you. Plus, get an extra day off for your birthday.
• Remote & flexible working – We’re fully remote with clear core hours, and no internal meetings on Friday afternoons.
• Home working & wellbeing budgets: Up to £1,200 / €1,200 annually to upgrade your remote setup (co‑working passes, equipment, etc.). Up to £150 / €150 monthly on anything that supports your wellbeing – from therapy to gym memberships to meditation apps.

Interview Process: Our processes normally take around 2‑3 weeks from first call to offer – please let us know about any adjustments to timelines that may be required.

• First call with our Talent Team (30 Mins). This is to understand your experience, motivations, and discuss the role in more detail.
• Behaviour Interview with our CTO (60 Mins). This is your chance to really understand the role, the expectations, and ensure alignment on ways of working.
• Technical Interview with the Team (90 Mins). You’ll meet with potential peers in this session and will discuss technical topics and experiences.
• Culture‑Add Interview with Stakeholders (45 Mins). The final session will be with two cross‑functional stakeholders, and will explore how your values align with ours, and is designed to be a genuine two‑way conversation, your chance to understand what it’s really like to work at tem.

We welcome applications from people of all backgrounds, experiences, and identities, including those that are traditionally underrepresented in the tech and energy sectors. If you’re excited about this role but not sure you meet every requirement, we’d still love to hear from you. Your unique perspective could be exactly what we’re looking for.