Back End Developer Engineer

London (GB)Octopus Energy Engineering ð – Backend /Full-time /HybridWe're making energy fair, clean, and simple for all using technology. Octopus Energy started with a bold idea: to build Britain's first truly digital energy supplier. By combining world-class tech with brilliant humans who care deeply about customers and driving the renewable energy transition, we made it happen and in 2025, we became Britain's largest energy supplier. Octopus Energy Group is a global energy transition collective. 10 businesses working across 4 continents to tackle energy transformation at nearly every front. And we constantly push to make energy better. And building innovative technologies that forge a path to a green energy system. We're united by a shared goal: to drive the global green energy revolution. We are looking for Backend Engineers (mid level) to join our Devices team and Low Carbon Tech team. Devices: Since launching our first piece of hardware, Home Mini, in 2022, followed by Cosy Heat Pumps in 2023 and the Charge EV Charger in 2025, we have continued to expand our portfolio of devices, helping customers make the green energy transition. You'll join a cross-functional team of backend and mobile engineers, working closely with our hardware team to extend and improve integrations for both existing and new devices in the Octopus Energy app. To make that happen, we are building a new, dedicated engineering and product team to completely re-imagine this process - making it fast, transparent, and predictable for our customers from day one. You'll help design and build the platform architecture, data integrations, and automations that eliminate real world friction. We embrace flat hierarchies and an open, agile culture that fosters innovation, flexibility, and creativity. If this sounds exciting, we'd love to chat. You'll be working in a codebase with ~100 merges per week from dozens of contributorsBuild and extend a Django backend serving multiple countries from a single codebase, making deliberate decisions about what should be generic vs. territory-specificIntegrate with upstream platform services (Kraken Customer, Kraken Field, Kraken Flex) that provide billing, CRM, auth, and device control - orchestrating across service boundaries dailyProactively identify and address monitoring, alerting, and observability gaps within your applications to ensure live systems run predictablyEngage confidently in feature technical designs, participate actively in code reviews, and provide clear documentation for your pull requestsUse systematic, structured approaches to resolve bugs or service blockers, and confidently step in to address incident management within your core domainWhat you'll needSolid backend foundations with a 3-4 year track record building web applications in Python, ideally with Django. Experience writing highly testable code (unit, integration, and functional tests run in parallel in CI) and working with relational databases and background task processingComfortable working in a large, multi-tenant codebase - navigating and extending shared abstractions, territory-specific behaviour, and integrations with upstream services. before building something bespokeComfortable with pace over process - we ship continuously, not in sprints, and trust automated guardrails (type checking, linting, CI) over manual gatesOpenness and excitement around integrating modern AI tools into daily development, testing, and debugging to maintain pace and spark innovationHigh initiative - able to break down engineering problems into shippable slices and make steady progress when requirements are evolving or domain context is still being builtA genuine curiosity about smart energy devices and the technology that connects them to people's homes. You won't need hardware expertise, but you'll be building the software that makes these devices useful to customersCoachable - genuinely interested in feedback and willing to adapt your approachOur core tech stack...Python, DjangoPostgreSQL, Celery, and asynchronous background processingAPI architectures: GraphQL, REST, modelling, writing fault-tolerant systems, and test-driven development (TDD)Also valuable...TypeScript, AWS Lambda, CDKDynamoDB, event-driven microservices, API GatewayDistributed architecture and scaling across servicesWe would prefer someone who can work in our London office but will consider remote candidates. On a call with one of our recruiters it's something we always cover as we genuinely want to match your experience with the correct salary. Where people work with autonomy, alongside a wide range of amazing co-owners, on projects that break new ground. Our Group CEO, Greg has recorded a podcast about our culture and how we empower our people. Visit our UK perks hub - Octopus Employee BenefitsIf this sounds like you then we'd love to hear from you, tell us what you care about, why Octopus feels right and most importantly, bring us the real you! Applying for jobs can be a bit scary so have a nose through some of our tips first ðP.Along the way, you'll chat with our recruitment team and your Recruiter will help you throughout different stages. Drop us a message at [email protected] and we'd love to help! Need any specific accommodations? Whether you require specific accommodations or have a unique preference, let us know, and we'll do what we can to customise your interview process for comfort and maximum magic! Studies have shown that some groups of people, like women, are less likely to apply to a role unless they meet 100% of the job requirements. Our people are our strongest asset and the unique skills and perspectives people bring to the team are the driving force of our success. Where necessary, we sometimes use AI tools to help with parts of our hiring process, like reviewing applications or assessing responses. We're lucky to receive a huge amount of interest, so these tools help our recruiters manage that volume, not replace them. Ultimately, every hiring decision (for example, whether to progress your application or not) is always made by a real person in our Talent team. If you'd like to know more about how we use your data, you can reach out to us via email at [email protected]. We're happy to help!