Senior Backend Engineer (Python)

Tokyo
Partial Remote
Full-time
January 6, 2026

About Octopus Energy

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 earlier this year, we became Britain's largest energy supplier.

In 2021, we brought this mission to Japan – the world’s largest liberalised energy market. Here, we are committed to making energy better for both customers and the planet, while driving the growth of green energy across the country by using smart technology. In our lean and fast-moving team in Japan, every idea and action has the power to create a real impact on both business and society. We’re looking for people who can build scalable, highly resilient platforms from the ground up.

We're scaling fast, and building the next generation of products to accelerate the green energy transition. Senior engineers will lead architectural decisions, guide system design, and mentor engineers as we scale. 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. Here in Japan we’re following in the footsteps of the UK, taking their learnings, and adopting products and experiences that customers love.

The Role

As a member of the Octopus Tech Team, 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. We’re expecting senior technical leadership, you will have tech decision-making authority, lead initiatives across domains, solve deep technical challenges, and align with global tech strategy. But you won’t be alone, you'll work side by side with teams across customer service, sales & marketing, operations, finance and data, and see the impact of your work in the real world, fast. You will also be a member of our global engineering community, where support is just a Google Meets or Slack message away.

There’s a couple of things you should be aware of about this role. You may initially be employed by Kraken Tech Japan, our sister company in Japan, then, at some future time in the near future, transfer your employment to Octopus along with other tech staff in our other markets across the world.

We’re expanding the scope of our tech team, and we are looking for Backend Engineers to join our team to lead backend development on some exciting new products. You will play a key role in leading the backend domain and building scalable, reliable services that power the future of energy in Japan.

What You'll Do

Build and operate Octopus Energy products for the Japanese market (with many on the horizon). Including driving architectural decisions, improving reliability and performance, and aligning global tech strategy with local requirements
Design and develop APIs to integrate with other systems and services. For example, lead API design standards, review complex integrations, and ensure consistency across services
Collaborate with international teams (UK, EU, APAC and USA) in global development projects
Develop and operate Octopus Energy’s core global backend system

What You'll Need

5+ years of professional experience in backend web application development
Hands-on experience with Python/Django or equivalent web frameworks
Architectural understanding, best practices, system decomposition, and mentoring others
Experience designing and operating RDBMS (e.g., PostgreSQL, MySQL)
Experience in team development using Git
Experience with secure, reliable, large-scale/ high-transaction systems
Experience developing and operating systems in cloud environments (AWS, GCP, or Azure)
Experience with microservice architecture
Ability to communicate in English (participating in meetings and discussions, reading and writing)
Interest in environmental issues and the energy industry

Who We Are Looking For

A self-sufficient person with a high level of initiative and who enjoys working in a fast-changing environment and can work autonomously
A strong team player who collaborates across teams and departments
Someone excited to solve social challenges through technology.
Ability to communicate in English is essential

Technical Expertise

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:

Python and 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

Bonus Points: AWS, Terraform, Packer, Consul, and Japanese language ability.

Our Process

Our process usually takes up to 4 weeks, but we’ll always do our best to flex around what works for you. Along the way, you’ll chat with our recruitment team and your Recruiter will help you throughout different stages. Got any burning questions before then? Drop us a message at talent@octoenergy.com and we’d love to help!

Octopus Energy is an equal opportunity employer. We're looking for genuinely decent people who are honest and empathetic. We encourage applications from all backgrounds as we believe unique perspectives are the driving force of our success.

APPLY NOW ➜🇯🇵 Residents Only

About Octopus Energy

Octopus Energy started with a bold idea: to build Britain's first truly digital energy supplier.

By combining world-class technology with talented people who care deeply about customers and the renewable energy transition, Octopus Energy achieved a major milestone by becoming Britain’s largest energy supplier earlier this year.

In 2021, Octopus Energy brought this mission to Japan, the world’s largest liberalised energy market. In Japan, Octopus Energy is committed to making energy better for both customers and the planet, while driving the growth of green energy nationwide. Within its lean and fast-moving Japan team, every idea and action has the potential to create a meaningful impact on both business and society.

Octopus Energy is scaling rapidly and building the next generation of products to accelerate the green energy transition. From making it easy to switch to heat pumps, solar power, and EVs, to launching smart tariffs and developing renewable energy generation at scale, Octopus Energy is tackling some of the energy industry’s most complex challenges with speed, creativity, and a strong focus on customers. In Japan, the team follows in the footsteps of the UK, applying learnings and adopting products and experiences that customers value.

As part of the Octopus Tech Team, you'll be given real ownership, a wide variety of responsibilities, and the opportunity to shape products that make a tangible difference in people’s lives by lowering bills, enabling greener living, and delivering experiences customers genuinely appreciate. You'll work closely with teams across customer service, sales and marketing, operations, finance, and data, and you'll see the real-world impact of your work quickly.

Octopus Energy is looking for people who want to be part of this journey and help shape the future of energy in Japan.

Japanese Language Policy
Octopus Energy requires good professional knowledge of the Japanese language.
Visa Sponsorship
Octopus is currently unable to sponsor visas for overseas applicants.
Paid Leave
Octopus Energy offers unlimited paid time off. Of course, members must coordinate with their teams when taking leave to ensure it doesn't impact projects, but beyond that the policy is flexible.

Octopus Energy also has a culture that allows people to take several weeks of vacation at a time if desired.

As long as team members get their job done, they can enjoy their leave. Simple.
Benefits
💹 Employee stock ownership plan

💻 New tech gear

🎓 Skill development support

👶 Financial support for childcare costs

👶 Shorter work hours for employees taking care of children

👶 Parental Leave

💚 Translation support (EN<>JP)

🧡 Interpretation support (EN<>JP)

💟 Complete health and social insurance
Remote Work
Octopus Energy is flexible with remote work, but if you are located in Tokyo, Octopus employees are preferred to be in the office 3 days per week.
Work style
Octopus Energy supports flexible working - They don't pay people to watch a clock. Need to catch a school pick up or have a new fridge delivered? No problem.

There are no specific "core hours", you just need to be visible and transparent. Most members tend to work from 9-5 in order to collaborate with the team.
Diversity
Octopus Energy is committed to making Octopus feel like home around the world. By bringing together diverse backgrounds and experiences, Octopus Energy works to make energy fair, clean, and simple for everyone through the use of technology, while building a business it can be proud of. Inclusion at Octopus Energy goes beyond ticking boxes; it starts with understanding differences, recognising where the company may have fallen short in the past, and making a genuine commitment to do better.

Octopus Energy is genuinely looking for thoughtful, honest, and empathetic people. Across its offices around the world, Octopus Energy strives to create an environment where everyone can be themselves and feel that their voice is heard and valued.

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. Whoever you are, if you like one of Octopus Energy's jobs, they encourage you to apply as you might just be the candidate they hire. People are Octopus Energy's strongest asset and the unique skills and perspectives people bring to the team are the driving force of their success. As an equal opportunity employer, Octopus Energy does not discriminate on the basis of any protected attribute. Their commitment is to provide equal opportunities, an inclusive work environment, and fairness for everyone.
Benefits and Culture
- The Octopus Energy culture - Octopus won the best company to work for in 2022. Our CEO, Greg has recorded a podcast about Octopus culture and how they empower their people. We’ve also been placed in the top 10 companies for senior leadership.
- Flexible working environment - genuine work life balance, Octopus treats you as a human, and do their best to make work and life merge smoothly together. You can read more info on Octopus Glassdoor page
- Relaxation - Octopus doesn’t count your holidays, they work hard, and so they know you need to play hard as well (within reason of course)
- Equity Options Scheme - you own your own part of the business, share options in the whole Octopus Energy Group so we all work together towards success
- Office culture - have a certain tech requirement? Octopus will do their best to get it. Octopus offices are also stocked with fruit, breakfast, great coffee and soft drinks. Weekly on a Friday we all get together (this happens virtually too) for company updates and drinks - we call it Family Dinner
- Your development is important - Octopus supports and helps with development including internal and external courses, learning, study support etc, all bespoke to you
- Our Octopus Benefits can be found here