Staff Full Stack Engineer - Sell-Side Growth

📈 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. 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, 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: We're hiring a Staff Software Engineer to join Origination & New Products, a new three-person squad inside Sell Side Growth. Sell Side Growth originates, contracts, and retains the renewable generators whose volume powers our platform - without generators, there's no product. The engine is scaling fast, and much of the manual process underneath today's pipeline - tendering, contracting, onboarding - needs to be rebuilt to handle that growth rather than buckle under it. This is a deep, hands-on IC role, not a squad-lead one - that's owned by the Staff/Senior Staff engineer leading the initiative. You're free to go all-in on the hardest technical problems: integration with Rosso (our pricing and settlement engine), Control Room (our core tendering and pipeline platform), and the deal-gating risk tooling that lets us take on genuinely new categories of commercial risk safely. We're not hiring for leadership polish here. We're hiring a ridiculously good engineer. In your first 12 months, you might: Own architecture-level decisions on the integration-heavy systems connecting Origination & New Products to Rosso, Data, and Billing. Help ship the first new product category live and generating qualified pipeline within 6 months. Help solve the tendering automation problem that currently limits how much volume the team can quote on - one of the highest-leverage levers for supporting our growth. Contribute to productising a currently manual, error-prone pricing process that's already turning away large, complex deals. Design deal-gating risk tooling for commercial risk categories that don't exist yet at tem, within our React/TypeScript and Python/AWS serverless stack. 🚀 Responsibilities: Go deep on hard systems: Own architecture-level decisions on integration-heavy systems, reasoning clearly about boundaries, contracts, and failure modes. Build for ambiguity: Take a piece of an undefined, commercially-driven problem and turn it into a shippable plan, within the direction your squad lead sets. Work across boundaries: Deliver on dependencies that sit with teams you have no authority over, such as Rosso, Data, and Billing, getting integrations right without needing to own the relationship. Build with impact: Design, build, and ship the hardest parts of the new-product build sequence yourself, backend-first but comfortable moving into the React/TypeScript front end when it matters. Maintain high standards: Write clean, well-tested code, contribute to code reviews, and help improve team practices and documentation. 🎯 Requirements: Must-Haves: Deep technical depth in backend and systems design, with a track record of owning architecture-level decisions on complex, integration-heavy systems. Comfortable in our core stack: Python, AWS serverless (Lambda, API Gateway, DynamoDB, EventBridge), and event-driven architectures. React/TypeScript exposure is a plus but not the bar. Comfort operating without a full spec: able to take a defined slice of an ambiguous problem and turn it into a shippable plan. Experience delivering work where a critical dependency sits with a team you have no authority over. Proven product delivery experience: experience as a Full Stack or Backend Engineer in a startup or fast-paced product environment, with ownership of complex projects from start to finish. Desirable: Prior experience mentoring engineers or setting technical direction, even without a formal leadership title. Not required. We'd rather have a brilliant engineer who has never led a squad than a mediocre one who has. Experience in energy, fintech, or another regulated, high-stakes commercial domain. Exposure to workflow orchestration, event-driven systems, or real-time pricing engines. Experience originating new product lines from scratch rather than only scaling existing ones. ✨ Benefits & Perks: Competitive salar y - our current band for this role is £104,000 or equivalent in local currency. We pay against a clear benchmark for your role and level. No fixed once- or twice-a-year cycle - pay moves when the evidence for it does. 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 🎉. Rem