Senior Backend Engineer

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.

Now, we’re scaling fast and building the next generation of products to accelerate the green energy transition. From making it effortless to switch to heat pumps, solar and EVs, to launching smart tariffs and creating renewable generation at scale, we’re solving some of the most complex challenges in energy with speed, creativity and customer obsession. We’re also enabling our global businesses to reach the full capability of what we’ve achieved in the UK, taking the learnings, products and experiences that customers love here and rolling them out worldwide.

At Octopus Tech, you’ll have real ownership, variety, and the chance to shape products that make a tangible difference in people’s lives - lowering bills, enabling greener living, and delivering experiences customers genuinely love. You’ll work side by side with teams across marketing, operations, and data, and see the impact of your work in the real world, fast.

We are looking for Senior Backend Engineers to join our Flexibility team.

The flexibility team is building the next generation of products and tools to make energy more flexible. These include our flagship Intelligent Octopus product automating demand shift for 300,000 customers with electric cars, home batteries or smart heating devices, saving 2 million customers money through Saving Sessions and Free Electricity Sessions, and managing 568MW of large grid-scale batteries to balance the system. The team develops products that are used by millions of customers, helping boost renewables use and decarbonise energy systems worldwide.

We embrace flat hierarchies and an open, agile culture that fosters innovation, flexibility, and creativity.

We don’t hang our personalities up with our coats and nor should you. At Octopus, we hire great people who get stuff done, all whilst being themselves.

If this sounds exciting, we’d love to chat.

What you'll need...

• 5+ years of professional experience in backend web application development
• Hands-on experience with Python/Django or equivalent web frameworks
• Strong systems design abilities, including microservices architecture
• Experience designing and operating RDBMS (e.g., PostgreSQL, MySQL)
• Experience with secure, reliable, large-scale/ high-transaction systems
• Experience developing and operating systems in cloud environments (AWS, GCP, or Azure)
• A self-sufficient person with a high level of initiative, able to work autonomously in a fast-changing environment
• A strong team player who collaborates across teams and departments, mentoring and coaching more junior developers
• Someone excited to solve social challenges through technology
• Interest in environmental issues and the energy industry

We're looking for someone with a general interest in technology and problem-solving; someone diligent and thoughtful. It would be helpful to have experience/expertise in the following (in rough priority order):

• Python
• Django (or equiv. web framework)
• Domain modelling
• Designing distributed systems, improving service reliability, and shaping long-term architectural strategy
• HTTP and REST APIs, GraphQL and other API technologies
• Writing robust and fault-tolerant software
• Celery and async processing
• Postgres
• Plus experience in the following would be a bonus: AWS, Terraform, Packer, Consul

💚Why else you'll love it here...

• 💰 Wondering what the salary for this role is? Just ask us! 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. The reason why we don't advertise is because we honestly have a degree of flexibility and would never want salary to be a reason why someone doesn't apply to Octopus - what's more important to us is finding the right octofit!
• 🎉 Octopus Energy Group is a unique culture. An organisation where people learn, decide, and build quicker. Where people work with autonomy, alongside a wide range of amazing co-owners, on projects that break new ground. We want your hard work to be rewarded with perks you actually care about! We won best company to work for in 2022, on Glassdoor we were voted 50 best places to work in 2022 and our Group CEO, Greg has recorded a podcast about our culture and how we empower our people.…