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. tem exists 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.

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.

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.
• Make architectural decisions that stick. Design and evolve a stateful, event‐driven system where domain logic is the primary source of complexity.
• 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.
• Lead across teams. Drive cross‐functional initiatives spanning engineering, product, data, and commercial stakeholders.
• 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.
• 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're comfortable working in Python. Our codebase is Python.
• You're strong with AWS serverless architecture. Hands‐on experience with Lambda, API Gateway, DynamoDB, and event‐driven, asynchronous workflows.
• 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 connect technical decisions to business outcomes.
• You lead cross‐team work. You've run initiatives that span engineering, product, data, and commercial stakeholders.

• 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.
• 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.
• Remote & flexible working - We're fully remote with clear core hours.
• Home working & wellbeing budgets: Up to £1,200 / €1,200 annually to upgrade your remote setup.

Interview Process: Our processes normally take around 2‐3 weeks from first call to offer.

We welcome applications from people of all backgrounds, experiences, and identities, including those that are traditionally underrepresented in the tech and energy sectors.