At a Glance
- Tasks: Lead a team to build and scale back-end services for an innovative electricity grid modelling platform.
- Company: Join TransitionZero, a climate tech non-profit dedicated to clean energy solutions.
- Benefits: Enjoy a hybrid work environment, competitive salary, and opportunities for professional growth.
- Other info: Be part of a dynamic team focused on creating accessible energy solutions.
- Why this job: Make a real impact in the energy transition while working with cutting-edge technology.
- Qualifications: 7+ years in back-end development, strong Python skills, and experience with cloud platforms.
The predicted salary is between 80000 - 100000 £ per year.
We are looking for an experienced Principal Back-End Engineer to lead the team building and scaling the infrastructure behind Scenario Builder, our electricity grid modelling platform. Scenario Builder is an in-browser platform that currently provides capacity expansion and dispatch modelling through an accessible no-code interface. The vision for Scenario Builder is to expand into power flow modelling to create a fully integrated grid modelling platform with the features and functionality needed to enable users to develop bankable scenarios that support energy investment decisions.
You will line-manage a small team of engineers while remaining a highly active individual contributor. You will own the technical shape of engineering work on the back-end team — leading planning, architecture, and code quality. You will work closely with the wider product and engineering team to design, develop, and maintain the back-end services that power our platform. This hybrid role is based out of our London office near Waterloo Station and reports to the Head of Platform.
Responsibilities
- Back-end development & architecture
- Design, develop, and maintain scalable back-end services and APIs using Python and modern frameworks (FastAPI).
- Design and build high-performance API endpoints to handle complex hierarchical data queries and multi-dimensional aggregations for grid modelling computations.
- Ensure system reliability, performance, and security through best practices in code quality, testing, and monitoring.
- Collaborate with front-end engineers to design and implement RESTful APIs that support our web application.
- Collaborate with data engineers and domain experts on the evolving core data model.
- Infrastructure & DevOps
- Manage and optimise cloud infrastructure (GCP) to support our computational workloads.
- Implement and maintain CI/CD pipelines to enable rapid, reliable deployments.
- Monitor system health and performance, proactively identifying and resolving issues.
- Implement and maintain infrastructure-as-code.
- Technical leadership & collaboration
- Participate and lead in code reviews, architectural discussions, and technical planning sessions.
- Own technical planning: break down roadmap items into well-scoped engineering work, lead estimation, and drive architectural decision records (ADRs).
- Collaborate with cross-functional teams, including product, data engineering, and modelling, to deliver impactful features.
- Set and uphold the team's technical standards — code quality, testing strategy, API design — through direct example and code review.
- People & line management
- Line-manage a team of 3–5 engineers: run regular 1:1s, support career development, and provide timely, constructive feedback.
- Partner with the Head of Platform on performance reviews and personal development plans.
- Act as the first point of escalation for day-to-day technical blockers.
About You
You should have a long-term commitment to advancing the energy transition and be driven to build robust, scalable systems that power our grid modelling platform. Passionate about creating highly performant back-end services, you understand the technical challenges associated with building niche B2B products that handle complex computational workloads. In addition to seeking out people with a proactive, problem-solving attitude and an eye for detail, as a growing organisation, collegiality and empathy for our coworkers are a requisite. While we are a rapidly growing tech startup, we are also a non-profit, so a high level of adaptability and willingness to approach challenges with creativity and curiosity is essential.
Skills & Experience
Essential
- 7+ years of experience in back-end software development, with strong proficiency in Python.
- Experience designing and building RESTful APIs and microservices architectures.
- Strong understanding of database technologies (PostgreSQL, Redis, Firestore), ORMs and data modelling principles.
- Experience with cloud platforms (preferably GCP) and containerisation technologies (Docker).
- Solid understanding of software engineering best practices, including testing, code review, and documentation.
- Excellent problem-solving skills and ability to work independently on complex technical challenges.
- Experience line managing or formally mentoring engineers, with confidence running 1:1s and supporting career development.
- Understanding of OAuth and web security best practices.
- Experience with AGILE/Scrum based ways-of-working.
Desirable
- Experience in the energy sector or with computational modelling/simulation software.
- Familiarity with scientific computing libraries (NumPy, Pandas) and optimisation frameworks.
- Experience with generative AI/LLMs in applied engineering contexts.
- Experience with infrastructure-as-code tools (Terraform, Terragrunt) and GitOps practices.
About us
TransitionZero is a climate tech non-profit founded in 2021. TransitionZero builds software to reduce the time to build clean energy at scale. We pioneer open-access and open-source tools that make electricity system modelling more transparent, accessible, and actionable for governments, financiers and grid operators worldwide. Our flagship tool, Scenario Builder, enables policymakers, planners and investors to rapidly build, analyse and share energy system and electricity grid models without coding expertise or external consultants. Supported by model-ready datasets, training and market insights, our tools strengthen in-house capacity and support resilient, affordable and locally-led energy transitions.
Principal Software Engineer (Back-End) in London employer: TransitionZero
TransitionZero is an exceptional employer for those passionate about advancing the energy transition through technology. Located in the vibrant heart of London, our hybrid work culture fosters collaboration and innovation while providing ample opportunities for professional growth and development. As a non-profit climate tech startup, we offer a unique chance to contribute to meaningful projects that have a real impact on global energy systems, all within a supportive and collegial environment.
StudySmarter Expert Advice🤫
We think this is how you could land Principal Software Engineer (Back-End) in London
✨Tip Number 1
Network like a pro! Get out there and connect with folks in the industry. Attend meetups, webinars, or even just grab a coffee with someone who works in back-end development. You never know who might have a lead on your dream job!
✨Tip Number 2
Show off your skills! Create a portfolio showcasing your projects, especially those involving Python and RESTful APIs. This is your chance to demonstrate your technical prowess and problem-solving abilities to potential employers.
✨Tip Number 3
Prepare for interviews by brushing up on your technical knowledge and soft skills. Practice coding challenges and be ready to discuss your past experiences managing teams and projects. Remember, they want to see how you think and approach problems!
✨Tip Number 4
Don’t forget to apply through our website! We’re always on the lookout for passionate individuals who want to make a difference in the energy sector. Your next big opportunity could be just a click away!
We think you need these skills to ace Principal Software Engineer (Back-End) in London
Some tips for your application 🫡
Tailor Your CV:Make sure your CV reflects the skills and experiences that match the job description. Highlight your back-end development experience, especially with Python and RESTful APIs, to show us you're the right fit for the role.
Craft a Compelling Cover Letter:Use your cover letter to tell us why you're passionate about the energy transition and how your background aligns with our mission. Share specific examples of your technical leadership and problem-solving skills to stand out.
Showcase Your Projects:If you've worked on relevant projects, whether in previous jobs or personal endeavours, make sure to mention them. We love seeing real-world applications of your skills, especially in building scalable systems or APIs.
Apply Through Our Website:We encourage you to apply directly through our website. It’s the best way for us to receive your application and ensures you’re considered for the role. Plus, it shows us you're keen to join our team!
How to prepare for a job interview at TransitionZero
✨Know Your Tech Inside Out
Make sure you’re well-versed in Python and the frameworks mentioned in the job description, especially FastAPI. Brush up on your knowledge of RESTful APIs and microservices architectures, as you'll likely be asked to discuss your experience with these during the interview.
✨Showcase Your Leadership Skills
Since this role involves line management, be prepared to talk about your experience mentoring engineers and how you handle team dynamics. Share specific examples of how you've supported career development and resolved technical blockers in the past.
✨Demonstrate Problem-Solving Prowess
Expect to face some technical challenges during the interview. Prepare to walk through your thought process on solving complex problems, particularly those related to back-end development and system reliability. Use real-world examples to illustrate your approach.
✨Align with Their Mission
TransitionZero is a climate tech non-profit, so it’s crucial to express your commitment to advancing the energy transition. Be ready to discuss why you’re passionate about building scalable systems for clean energy and how your values align with their mission.
